The very best parts of Roger Federer and Rafael Nadal’s FedEx ATP Head2Head rivalry will remain unquantifiable forever. How their games have evolved throughout their careers. The passion they share for tennis. The feelings of excitement they’ve provided millions of fans during the past two decades.

But certain aspects of their rivalry, one of the best in all of sport, can be counted. And when you’ve played each other 37 times over 14 years and your match-ups have decided 23 tour-level titles, the numbers add up quickly.

To begin: They’ve spent a lot of time together. Nadal and Federer have been on court together for the equivalent of almost four full days – three days, 17 hours and 16 minutes, to be precise. If you’re thinking about that in terms of a workweek, that’s one busy week – 89 hours.

They’ve played more than 7,000 points, more than 1,100 games and more than 100 sets. They’ve had their share of faults – 126 double faults to be more accurate – but they’ve also aced each other dozens of times, and that’s not hyperbole.

To relive all 37 matches they’ve played, click here. For more stats, keep reading.

By The Numbers: Federer v. Nadal

Alexander Zverev started March strong and ended his month with a vengeance. And the 19-year-old German, ranked World No. 20 in the Emirates ATP Rankings, notched a few career milestones along the way.

Continuing his stranglehold on the Emirates ATP Race To Milan, Zverev began March with 340 points in the Race, holding a 45-point lead ahead of then No. 2 Daniil Medvedev. As of 3 April Emirates ATP Rankings, he leads the pack with 565 points, 260 points ahead of Medvedev.

Pre-Register for Tickets To The Next Gen ATP Finals

At the BNP Paribas Open, the first ATP World Tour Masters 1000 tournament of 2017, after a bye in the first round, Zverev handily beat Facundo Bagnis to set a third-round clash with Nick Kyrgios, their first tour-level meeting and thus beginning a rivalry that will be one to watch for years to come.

“It will be a very exciting match, because he’s played well this year and I’ve played well this year too,” Zverev said ahead of the match. “I don’t want to say I can be the champion by the end of the next week, but I feel I can play great tennis and I can beat anybody. I have the toughest quarter of the draw and I have a feeling the champion will come out of this section. The next few rounds will be very, very difficult for all us.”

The Aussie claimed the win 6-3, 6-4, but the pair would have a rematch sooner than they thought. But before we get ahead of ourselves, the German teen made waves at the start of his Miami Open presented by Itau campaign.

Following a bye in the first round, he had no trouble getting past Yen-Hsun Lu 6-0, 6-3, before big-server John Isner provided an exceptional challenge. A fourth-round berth in the Masters 1000 tournament in South Florida was Zverev’s prize after saving three match points to beat the American 6-7,(5), 7-6(6), 7-6(5).

Next was a chance to oust top seed Stan Wawrinka, and Zverev didn’t hold back, coming from a set down to run away with the Round of 16 clash and claim a 4-6, 6-2, 6-1 victory. With that, he booked a spot in the quarter-finals of a Masters 1000 for the first time.

“I had to be aggressive. I felt like he was the one controlling all the points all the time, so I had to change that. It worked out well for me. Happy to be in the quarter-finals now. Hopefully I can play as great as I did today,” Zverev said after his Wawrinka triumph.

As if his last two matches weren’t entertaining enough, it was time for fireworks in Florida: Zverev was to face Kyrgios for the second time in March in what proved to be a spectacular match. Thursday night, under the lights, Zverev pushed Kyrgios further than their first meeting, forcing the Aussie to require six match points to capture the emotion-filled win 6-4, 6-7(9), 6-3.

The towering German will now look to extend his lead in the Emirates ATP Race To Milan on the clay swing in Europe, where he performed well in 2016. He advanced to the semi-finals in the BMW Open by FWU, the final in the Open de Nice Cote d’Azur, while also reaching the third round at Roland Garros (All lost to Thiem).

Should Zverev manage to maintain his level from March, the ATP World Tour could witness a few more career milestones in the near future.

View Full Emirates ATP Race To Milan

Kontinen New No. 1

Finland’s Henri Kontinen on Monday became the 50th player in the history of the Emirates ATP Doubles Rankings to rise to No. 1, following a strong run of form with his regular partner John Peers over the past six months. Kontinen’s rise to the summit ends the 38-week stint at the top spot for France’s Nicolas Mahut.

Read: Kontinen No. 1 Tribute

Kontinen and Peers have put together a 25-6 match record since mid-October 2016, picking up titles at the Paris Masters (d. Herbert-Mahut), the ATP Finals (d. Klaasen-Ram) and the Australian Open (d. Bryans). They were also runners up at the Shanghai Rolex Masters (l. to Isner-Sock). In 2017, they are the early pace-setters in the Emirates ATP Doubles Race To London.

Kontinen leads Peers (7,560) by 140 points in the Emirates ATP Doubles Rankings, with Bob Bryan and Mike Bryan tied third, narrowly behind on 7,430 points. The Bryans, who have finished in year-end top spot on 10 occasions, had the opportunity to return to No. 1 if they had lifted their fifth trophy at the Miami Open presented by Itau. The twins lost to Nicholas Monroe and Jack Sock in the semi-finals.

Kubot/Melo Enjoy Strong Start

One of the season’s new teams, Lukasz Kubot and Marcelo Melo, are up to No. 2 in the Emirates ATP Doubles Race To London for one of the eight spots at the ATP Finals, to be held at The O2 from 12-19 November. After a relatively slow start (4-5 record), the Polish-Brazilian tandem hit their stride in the March sunshine by beating Jamie Murray and Bruno Soares twice, en route to finishing runner-up at the BNP Paribas Open (l. to Klaasen-Ram) and capturing the Miami crown (d. Monroe-Sock).

Buy Tickets For London

Raven Klaasen and Rajeev Ram look to be backing up their late 2016 charge with the Delray Beach Open crown (d. Huey-Mirnyi) and four Match tie-break wins for Indian Wells glory.

Read: Five Things We Learned From Miami

Former No. 1s Close In On Milestones

Keep an eye on Max Mirnyi, who first became No. 1 as a 25 year old on 9 June 2003, as he continues his quest for the 50th doubles trophy of his career in partnership with Treat Huey.

Also, Nenad Zimonjic is seven match wins (693) from becoming the 10th player in ATP World Tour history to record 700 match wins and joining Daniel Nestor, Bob Bryan, Mike Bryan, Todd Woodbridge, Mark Knowles, Sherwood Stewart, Leander Paes and Jonas Bjorkman in the ‘700 Wins Club’. Zimonjic, 40, who first rose to No. 1 on 17 November 2008 and spent 50 weeks in top spot, clinched his 54th career crown in February at the Garanti Koza Sofia Open with Viktor Troicki.

What to call the beginning of Roger Federer’s 20^th year on the ATP World Tour?

In January, we would have used adjectives such as “hopeful” or “upbeat”. Federer, describing himself, picked “rejuvenated” and “refreshed”.

In what looks like prescient language now, three months on, the Swiss veteran said at the start of the year, “I do believe it could be very beneficial for the future of my tennis career that I’ve had this six-month layoff… I feel rejuvenated, refreshed. Maybe mentally I needed this rest more than I thought I would. Maybe also my body needed a rest more than I thought I would.”

But now, after Federer has rolled through the Australian Open, the BNP Paribas Open in Indian Wells and the Miami Open presented by Itau, his earlier adjectives no longer work.

Perhaps “unbelievable”? None of this was predicted – not by Federer, not by his coaches, not by tennis pundits and maybe not even by the millions of fans across the world who scream for the Swiss star. But whatever term you pick, there’s no mistaking what Federer’s start has added to his place among the best in the game.

By capturing the season’s first three “Big Titles”, Federer has extended his “Big Titles” lead against long-time rivals Novak Djokovic and Rafael Nadal. The Swiss right-hander now has 26 ATP World Tour Masters 1000 crowns and 50 overall “Big Titles”. That puts Federer three “Big Titles” ahead of Djokovic and eight ahead of the left-handed Spaniard.

Current and Former Champions’ Big Titles Won (Records Since 1990)

 * Becker’s four other Grand Slam titles came before 1990.
** Edberg’s three other Grand Slam titles came before 1990.

“Once you win a big tournament like the Australian Open, or any big tournament for that matter, you can just bank usually on some confidence,” Federer said on Sunday after beating Nadal for his third Miami title. “That confidence gets you through a lot of the tough matches that nobody ever speaks about again.”

To earn that belief, in Melbourne, the 17th-seeded Federer had to beat Tomas Berdych, Kei Nishikori, Mischa Zverev, Stan Wawrinka and Nadal for his 18^th Grand Slam.

In Indian Wells, Federer met Nadal, not in the final, but in the fourth round, and then faced rising American Jack Sock before again beating Wawrinka in the final.

The past two weeks in Miami, Federer had to overcome Juan Martin del Potro and Roberto Bautista Agut to reach the last eight. In the quarter-finals, Federer saved two match points against Berdych before outdoing Nick Kyrgios in an epic semi-final and again beating Nadal in the final.

Federer’s stats from the three big tournaments: 18 wins, zero losses; a 7-0 record against the Top 10; a 10-2 record in tie-break sets, and the most important number: Three more “Big Titles”.

“I can’t explain. I told Severin [Luthi], my coach, when I was warming up, if I would have just played the Miami finals, no Indian Wells, no Australian Open, we would still be very happy right now,” Federer said on Sunday. “But I have way more, so that’s why I was trying to remind myself just to play without pressure. Just do it one more time and go out there and be brave on the big points. I think I was able to do that.”

“Be brave” – it’s the same mantra Federer carried with him during the Australian Open final, the first time he surprised Nadal with his flat backhand, and likely the same advice he brought to the court in Indian Wells. “Be free in your head, be free in your shots, go for it. The brave will be rewarded here,” Federer said in Melbourne.

Watch & Vote: March Masters Golden Hot Shot

His “Big Titles” lead is hardly secure, though, especially considering his announcement that he’ll take an extended break and likely play only Roland Garros on the clay. Three Masters 1000 tournaments sit between now and the season’s second Grand Slam, which starts 28 May, including the Monte-Carlo Rolex Masters, the Mutua Madrid Open and the Internazionali BNL d’Italia in Rome.

All three other members of the “Big Four” have brought home hardware from those clay-court Masters 1000 events. Djokovic and Nadal have won all three titles in their careers, and Andy Murray is missing only the Monte-Carlo crown.

Just last year, Nadal won his ninth Monte-Carlo title, Djokovic claimed his second Madrid trophy, and Murray celebrated his first Rome championship. Djokovic also still remains the all-time leader in Masters 1000 titles with 30.

“Unpredictable”? You could say that about Federer’s first three months, and about the next few months of the ATP World Tour season.