After eight days of thrilling Nitto ATP Finals action at The O2 in London, Alexander Zverev earned the biggest title of his career. The 21-year-old German defeated World No. 1 Novak Djokovic 6-4, 6-3 on Sunday, but which moment did fans inside the world famous venue in South East London connect most with? Infosys ATP Fan Meter has the answer.

Recording decibel levels inside Centre Court throughout the tournament, the Top 10 moments from the elite eight-man event have been confirmed. Six of the eight players competing for the trophy at the season finale made the Top 10 winning list, with all eight man featuring in matches containing Top 10 moments.

Leading the way, with three entries in the Top 10, is Roger Federer. The six-time champion was responsible the loudest reaction of the tournament in his opening match against Kei Nishikori, with the crowd reaching 110dB as they rallied behind the 16-time ATPWorldTour.com Fans’ Favourite award winner after an exquisite forehand lob in the second set. That level of sound isn’t unfamiliar to regular visitors to The O2, but this time there were no microphones, drums or guitars.

The opening singles match of the tournament provided the second loudest moment of the event, as Dominic Thiem fired a cross-court forehand winner late in his epic second-set tie-break against Kevin Anderson. Despite falling to the South African in straight sets, Thiem won the hearts of the crowd, who responded with an impressive 108dB for his fearless efforts. Thiem almost beat that figure in his following match, notching 106 dB with a solid overhead under pressure in the second set against Federer.

Runner-up Novak Djokovic makes two appearances in the list, hitting 107dB and 106dB in his first and final Group Guga Kuerten encounters, respectively. The five-time champion impressed the London crowd with a backhand winner down the line against Isner in his opening match, before stunning Marin Cilic with his phenomenal defensive skills as he completed group play with a 3-0 record.

No list would be complete without an entry from the champion in the final match of the ATP World Tour season. With 104 dB, Zverev earned his spot in the Top 10 late in the first set of the championship match. The German became the first man to break Djokovic’s serve throughout the tournament as the World No. 1 misfired on his forehand side.

Marin Cilic and Kei Nishikori complete the Top 10, lifting the crowds in their fourth appearances at The O2. The 2014 US Open finalists proved finesse can be just as effective as power, with Cilic clocking 105dB for a stellar drop volley against Zverev and Nishikori hitting 104dB for an imaginative slice backhand in his round-robin loss to Anderson.

Alexander Zverev hit the high point of his still-young career on Sunday, defeating World No. 1 Novak Djokovic to lift his first Nitto ATP Finals title at 21 years, 212 days old. It is the German’s 10th tour-level triumph, and his biggest yet.

But Zverev has accomplished a lot at his young age. He has already captured three ATP World Tour Masters 1000 titles and earned 23 victories against opponents inside the Top 10 of the ATP Rankings. And by virtue of his win over Djokovic on Sunday, Zverev became the youngest Nitto ATP Finals champion since Djokovic himself a decade ago.

So one may wonder, where were some of the best players in the game when they were Zverev’s current age? ATPWorldTour.com flashes back to take a look at where all four active players who have reached No. 1 in the ATP Rankings were when they were 21 years, 212 days old.

Roger Federer
Considering Federer now has 99 tour-level trophies, one might be surprised that he owned just six when he was Zverev’s age.

The Swiss had climbed to No. 4 in the ATP Rankings, and won an impressive 178 tour-level matches. And Federer had won his first ATP World Tour Masters 1000 title 10 months earlier in Hamburg, beating two opponents inside the Top 10 en route to what was the biggest triumph of his young career.

But it was after he was Zverev’s age that Federer broke out. In March of 2003, when Federer was 21 years, 212 days old, he had already lifted two trophies that season. But the Swiss would go on to win five more that year, including his first Grand Slam championship at Wimbledon and his first of a record six Nitto ATP Finals crowns in Houston, where he would beat World No. 1 Andy Roddick, World No. 2 Juan Carlos Ferrero and Andre Agassi twice. The following February, Federer ascended to the top of the ATP Rankings for the first of what has been 310 weeks at World No. 1.

Rafael Nadal
The Spaniard achieved an incredible amount by the time he was Zverev’s age. Nadal had already won 23 tour-level titles, including his first nine ATP World Tour Masters 1000 crowns and three Coupes des Mousquetaires at Roland Garros.

Perhaps what stands out the most is that in 2005, when Nadal turned 19 years old, the Spaniard won 11 tour-level titles. To this day, Nadal has not lifted more trophies in a single season since. Nadal claimed the first four of his record 33 ATP World Tour Masters 1000 titles that year, and he hasn’t looked back since.

When Nadal was Zverev’s age, he had already amassed more than 250 match wins. And to put that in perspective, there are less than 200 players in history who have earned that many tour-level victories, according to the FedEx ATP Performance Zone.

Novak Djokovic
The Serbian, had recently captured his first Nitto ATP Finals trophy when he was 21 years, 112 days old. That was Djokovic’s 11th tour-level title, and it came at the close of his best season to date.

In 2008, Djokovic claimed four victories, all of which were ‘Big Titles’. The current World No. 1 won his first Grand Slam championship at the Australian Open that year, earned his third and fourth ATP World Tour Masters 1000 titles in Indian Wells and Rome, and won at least 60 matches for the second consecutive year.

Djokovic spent the entirety of 2008 at No. 3 in the ATP Rankings, and he earned 11 victories against Top 10 opponents that season. And there was no stopping from there, as Djokovic would win five titles in 2009, and the rest is history.

Andy Murray
The Scot had climbed to a career-best No. 4 in the ATP Rankings when he was Zverev’s age. Murray won an impressive five ATP World Tour titles in 2008, bringing his career total to eight at just 21 years of age.

Murray also claimed his first two ATP World Tour Masters 1000 titles that season, triumphing in Cincinnati and Madrid, when the Spanish event took place later in the year on indoor hard courts. Murray also advanced to his maiden Grand Slam final in 2008, defeating Nadal en route to the championship match at the US Open, where Federer would claim his fifth consecutive trophy.

And while Murray fell short in that match, he won three of his four FedEx ATP Head2Head meetings against Federer that year, and his win against Nadal in Flushing Meadows was his first victory against the Spaniard in six tries.

Finishing the season inside the Top 100 of the ATP Rankings is a special achievement for those competing on the ATP Challenger Tour. It marks the culmination of a year of hard work and often signals a turning point in a player’s career.

But few Top 100 ascents are as dramatic as this. Reilly Opelka opened the month of September at No. 173, with a mountain to climb to crack the century mark. Having struggled with a bout of mononucleosis over the U.S. summer, the 21-year-old needed to find his form in a hurry. What resulted will go down as one of the most memorable storylines of the Challenger season.

Opelka had claimed just 17 match wins during the year, as he stepped on the hard courts of windy Chicago in the first week of September. He would double that total in the coming months, capping his Top 100 ascent with a stunning 17-4 stretch. It all kicked off with back-to-back finals in Chicago and Cary and culminated with consecutive titles in Knoxville and Champaign. That’s four final appearances in just six tournaments following the US Open. 

On Saturday, Opelka blasted to a career-high No. 98 in the ATP Rankings behind a 7-6(6), 6-3 win over Ryan Shane in the final of the JSM Challenger of Champaign-Urbana. He needed to sweep both indoor events in Knoxville and Champaign to conclude his season and he did just that, reeling off nine straight matches with aplomb. Playing with poise and maturity from the baseline, the 6’11” American did not only rely on his seismic serve. Armed with a more consistent and patient ground game, coaches Jay Berger and Jean-Yves Aubone have guided their young charge to new heights.

Opelka Fast Facts
– Concludes the season in second place among Challenger win-loss percentage leaders (.756), behind only Vasek Pospisil (.784).
– One of six players to win at least three titles in 2018, joining Guido Andreozzi (4), Pablo Andujar (3), Hugo Dellien (3), Christian Garin (3) and Jordan Thompson (3).
– First American to win three titles in a single season since 2014 (Bradley Klahn and Sam Querrey).
– Joins Frances Tiafoe and Taylor Fritz as Americans aged 21 & under to feature in the year-end Top 100.

After winning in Champaign, Opelka spoke to broadcaster Mike Cation…

You said last week that Top 100 didn’t really matter to you, because of the long-term goals. That being said, now you’re there and you’ve guaranteed yourself Australian Open main draw. That has to mean something at this point.
Yeah, being in the main draw of Australia is huge. It allows me to go there and play two tournaments before the Australian Open. Usually I’ll have to play qualies the week before and it’s a long trip over there just for that. You might just play one match and then qualifying, which is brutal. From that standpoint, it’s huge. Like I said last week, Top 100 is not something I’m celebrating, but yes, I’m stoked to be there.

Two straight titles to get there is pretty hard to do. In your first couple matches in Champaign, your game wasn’t entirely there. What turned on as the week progressed?
I was focused, but I just played another guy [Lloyd Glasspool] with a big serve. And then [Kaichi] Uchida was playing insane in the second round. The tough moments in the tournament were early on and then in the quarter-finals it was just a great match-up for me. On Friday, it was extremely physical [against Tommy Paul], so I wasn’t 100 per cent confident in my body today. But I knew that playing Ryan, he would be serving big and looking to end points quick. I didn’t have to rely on moving and being physical to win the match.

Tommy Paul is a very close friend of yours. How awkward was it to play him for the first time as pros, in the semi-finals?
I didn’t feel it was awkward, actually. We know each other so well and have practised a ton together. We know each other’s games, but it did take me a while to get going in that match. I started slow. Once that happened, we played great tennis. From 2-all in the second set until the end of the match, it was high quality. I didn’t serve my best, so I won a lot of points from the baseline and was just scrapping. We had a 40-ball rally on the first match point. I had to win in a different way from how I’m used to winning. 

✅ Back-to-back #ATPChallenger titles
✅ Top 100 debut
✅ First ?? to lift three ? in a single season since Bradley Klahn in 2014@ReillyOpelka is the champion in Champaign, capping his 2018 campaign in dominant fashion. pic.twitter.com/ddnNK3J6Zj

— ATP Challenger Tour (@ATPChallenger) November 17, 2018

It was completely different in the final against Ryan. He’s playing some incredible tennis this week and showing everyone what he’s capable of, reaching his first final. What did you see from him and how did you combat that?
I think he’s just disrupted a lot of guys. He was playing much more consistent with the same aggression. That’s huge. In baseline points, I didn’t feel comfortable at all. I’d hit a huge shot and he responded right back. Granted, he missed some big shots that he shouldn’t have, including that break point that gave me the first break. Maybe that’s the downside to his style, where you can’t control it in the big points. But that’s what won me the match today.

You played pretty well under pressure the past two weeks. How do you bring that into next year? What will you do with a six-week off-season in front of you?
I actually don’t think it’s something I can bring into next year. I have six weeks off and I’ll take a short break and then it’s five weeks of getting better. We looked at a lot of stats and watched a lot of my matches last year. We’ll do the same this year. Putting this year behind us what we need to do and we’ll look at what flaws need to be fixed for next year.

If you take out the struggles with mono and you look at the year as a whole, what you’ve done is pretty important. Just in terms of your growth and your development. You are at the point where you can start playing more and more ATP events so you are not at the Challenger level. How important is that for you in 2019?
It’s huge. I hope I can make a nice transition on the ATP World Tour. I’m not saying I will or it will be easy, but it’s definitely not my last Challenger. I have the opportunity to go to Australia and train with a couple tour events and prepare for the Aussie Open. I’ve never had that chance before.

Last week you said you weren’t going to celebrate your title in Knoxville, but now you don’t have anything to worry about with a complete week off coming up. How are you going to celebrate with your team, family and friends?
My favourite restaurant is in Chicago. It’s called Boca. I’m going to try to take my talents there and probably won’t be able to walk out because I’ll be eating so much. I went there every night with Michael Mmoh during the Chicago Challenger. He’ll also confirm that it’s the best restaurant we’ve been to. It’s on the agenda.

Alexander Zverev’s holiday in the Maldives will be that much more enjoyable next week after the 21-year-old followed in the footsteps of fellow German Boris Becker, who won the last of his three season finale titles in 1995, with victory over Novak Djokovic at the Nitto ATP Finals on Sunday. Zverev has also finished the year among the Top 4 in the ATP Rankings for a second straight season.

Zverev, who was emotional and admitted to being dazzled by the silver trophy in his post-final press conference, admitted, “This trophy means a lot, everything, to all the players. I mean, you only have so many chances of winning it. You play against the best players only. How I played today, how I won it, for me, it’s just amazing.”

As the youngest singles champion at the season finale since Djokovic clinched the crown in 2008, aged 21, when the event was played in Shanghai, Zverev fell to his knees in celebration on court after beating World No. 1 and five-time former titlist Djokovic 6-4, 6-3 at The O2 in London.

“I fell to my knees, so my knees kind of hurt,” said Zverev. “Apart from that, I was very happy. Obviously, it’s quite astonishing, winning this title, beating two such players back-to-back, Roger [Federer] and Novak, in semi-finals and final. It means so much. I’m incredibly happy and incredibly proud of this moment right now.”

Zverev recovered from a 6-4, 6-1 round-robin loss to Djokovic on Wednesday to become the first player to beat Roger Federer (in Saturday’s semi-finals) and Djokovic at the Nitto ATP Finals. He is the first player since 1990 to beat the top two seeds, replicating the feat of Andre Agassi who knocked out Becker in the semi-finals and Stefan Edberg in the final.

In his eighth tournament since teaming up with Ivan Lendl, Zverev reflected on the influence of the former World No. 1. “He obviously analysed the match that I played with him a few days ago [and] told me a few things I had to do different,” said Zverev. “I was more aggressive today. I tried to take the ball earlier… But my Dad is the one that gave me the base. My Dad is the one that taught me the game of tennis. My dad deserves the most credit out of everyone… I’m very thankful to him for that. Obviously [with] Ivan, the experience he has on and off the court, is amazing. That helped me, as well, to kind of play the two matches that I played back-to-back now.”

Zverev completed the season with an ATP World Tour-best 58 match wins on the season (58-19 overall), which includes three other trophies at the Mutua Madrid Open (d. Thiem), the BMW Open by FWU (d. Kohlschreiber) and the Citi Open in Washington, D.C. (d. De Minaur).

“[Djokovic and Federer] are still going to be the guys to beat at the big tournaments,” said Zverev. “[But] I will do everything I can to get better, to compete with them always. I feel like I’m doing that. But I still have a lot of things to improve. I’m still very young. Hopefully, next year, I’ll be able to play better tennis than I did this year, even though it’s been a good year.”