Throughout my 16-year career, I’ve played in hundreds of tennis stadiums. I’ve slid on the grass on Centre Court at the All-England Club. I’ve gazed at the Mediterranean Sea from the red clay of the Monte-Carlo Country Club. In Indian Wells, I’ve lost track of time staring at the Palm Desert mountains while in town for the BNP Paribas Open.

But nowhere, including the many indoor tournaments we play annually, prepared me for playing at the Barclays ATP World Tour Finals. To put it simply, everything is different at The O2.

Let’s start with the lights. For about 10 months of the year, we play our matches outside. Sometimes the sun blocks your vision of your ball toss. Other days, clouds shield the sky and you play under overcast skies. 

But at The O2, we have plenty of light, and it’s all on you. Maybe it’s this way because of the many concerts the venue hosts, but, during play, the arena can feel like a theatre. The lights – the very bright lights – are on us, the performers, and the bulbs on the crowd stay dimmed.

This is a good thing, too. It’s so much easier to see the ball inside The O2 than anywhere else on the ATP World Tour. The theatre analogy works to describe the tennis crowd in London as well. Most crowds are respectful, maybe cheering at climax moments – tie-breaks or whenever Andy Murray steps within 50 metres – but the majority of the time, London tennis fans watch attentively and cheer when appropriate.

The lights also shine on you when you walk onto the court during one of our sport’s most special on-court introductions. The videos on the jumbo-tron before the match. The public announcer shouting your name before you walk through the tunnel. It’s a show that happens to take place before a tennis match, and I’m enjoying every moment of it. Even the most basic part of our game – the sound of the ball hitting the racquet – hits your ear differently because of the acoustics of The O2.

I’m 35 years old – 200 in tennis years – and when you’ve played professional tennis for as many years as I have, you start to think you’re used to everything. You think you’ve seen all the big crowds, played under the brightest lights and in our sport’s biggest stadiums.

But then you make your debut appearance at the Barclays ATP World Tour Finals, and you get to experience something entirely new.

Feliciano Lopez spoke with Jonathon Braden

The winner of Thursday’s match at the Barclays ATP World Tour Finals between Austria’s Dominic Thiem and Canada’s Milos Raonic will qualify for Saturday’s semi-finals as the runner-up in Group Ivan Lendl. 

Thiem is the youngest man to win a singles match at The O2 since 2009. Any young Austrian tennis player will find himself toiling in the long alpine shadow of Thomas Muster, a former World No. 1. And yet it’s perfectly possible that Thiem, a debutant at the season finale, could today out-perform Muster by qualifying for the semi-finals. For all his other achievements, ‘The Iron Man of Tennis’ never did that.  

“A star is born – big hug,” Jose Mourinho wrote on the back of his VIP pass to the Barclays ATP World Tour Finals, which he gave to Thiem backstage on Sunday. Manchester United’s manager, who likes his tennis, appreciated the quality of Thiem’s play on that opening afternoon, with the 23-year-old snaffling a tie-break 12-10 against Novak Djokovic before losing in three sets. And there was another significant moment for Thiem on Tuesday when he registered his first victory at the tournament with a three-set win over Gael Monfils, so becoming the youngest man to win a singles match at the event since 2009.  

Thiem has already played a lot of tennis at The O2 this week – six sets so far – just as he has played a lot of tennis this season. In a busy year, Thiem has won four titles, which is more than anyone else apart from Andy Murray (8) and Djokovic (7). Raonic, who pushed Djokovic to two tie-breaks on Tuesday evening, has a record in London to maintain. After finishing as the runner-up at The Queen’s Club this year, and also playing for the title at Wimbledon – on both occasions he was rebuffed by Murray – can he go on to reach a third final of the season in London? 

Defending champion Novak Djokovic, who has won all four of his previous matches against David Goffin, meets the Belgian alternate in Group Ivan Lendl this afternoon. 

Djokovic has Inspector Gadget-like reach and legs that are seemingly made of rubber. Any time he performs the splits on a hard court – as he just might today – there should really be a public health warning: “Don’t try this at home.”

Watching Djokovic, you’ll be reminded of how far tennis has travelled since its beginnings in 19th-century tea parties on vicars’ lawns. Or, indeed, how far it has travelled since the 1980s, the decade being celebrated at the Barclays ATP World Tour Finals this week. 

Here’s something else to admire – Djokovic’s run at this season finale, with the Serbian attempting to win the tournament for a fifth successive year and for a record-equalling sixth time overall, which would bring him parity with Roger Federer. But Djokovic hasn’t had it easy so far at The O2 this November – he lost a 12-10 tie-break to Dominic Thiem on Sunday before winning in three sets, and he fended off Milos Raonic on Tuesday in a couple of tie-breaks. Even so, Djokovic maintained his unbeaten record against both those opponents. 

Djokovic was supposed to be playing Gael Monfils, a Frenchman he has conquered in all 13 meetings, in this afternoon’s singles match. But with Monfils, who had lost his opening two matches, withdrawing from the tournament last night because of a worsening rib injury, Djokovic’s opposition will instead be Goffin. And even with that change, Djokovic goes into another Group Ivan Lendl match looking to preserve his ‘perfect’ record against that day’s opponent as he leads the alternate 4-0 in their FedEx ATP Head2Head. The last of Djokovic’s victories over Goffin, the World No. 11, came this year at the ATP World Tour Masters 1000 event in Miami. 

DAY 5 PREVIEW

While four-time reigning Barclays ATP World Tour Finals champion Novak Djokovic has already locked up a spot in the semi-finals by winning Group Ivan Lendl, the two youngest players in this year’s field, Milos Raonic (25) and Dominic Thiem (23), battle it out Thursday with the winner going on to the final four.

In the opening singles match, Djokovic brings a 4-0 career FedEx ATP Head 2 Head record against alternate David Goffin, who replaced Gael Monfils. The Frenchman withdrew on Wednesday with a rib injury. The 25-year-old Belgian has put together his best season and he will finish a year-end high No. 11 in the Emirates ATP Rankings. His best result was a runner-up in Tokyo last month (l. to Kyrgios). He also advanced to four semi-finals, including back-to-back ATP Masters 1000 events in Indian Wells and Miami. He is trying to become the first alternate to win a match since Janko Tipsarevic (d. Djokovic) in 2011. Djokovic won the last meeting 76 64 on Apr. 1 in the semi-finals at Miami. Djokovic, who advanced to the season finale semi-finals for the fifth straight year (and seventh overall) with his 76 76 win over Raonic on Tuesday, has earned 400 Emirates ATP Ranking points so far.  He will have 11,380 points on the season if he beats Goffin. Andy Murray has 11,310 points after his 3h, 20m victory over Kei Nishikori on Wednesday. Djokovic has won 20 of his past 21 matches at The O2 since 2012 with his only loss coming to Federer last year in the second round robin match. Djokovic is attempting to finish group play undefeated (3-0) for the fourth time in the past five years.

In the evening session, Raonic and Thiem square off for the second time. In their previous meeting in the quarter-finals at ATP Masters 1000 Cincinnati on Aug. 19, Raonic won 63 64. Both players are 1-1 this week in Group Ivan Lendl, defeating Monfils and losing to Djokovic. The winner of this match will mark a historic first singles semi-final appearance from Canada or Austria in the ATP Finals (since 1970). Raonic is trying to reach his ninth semi-final of the season while Thiem is attempting to advance to his 11th semi-final. If he beats Raonic, Thiem would be the youngest semi-finalist at the season finale since Juan Martin del Potro (21) reached the final in 2009 (l. to Davydenko). Raonic and Nishikori are chasing current No. 3 Wawrinka to finish No. 3 in the Emirates ATP Rankings for the first time. Wawrinka has 5,315 points and leads Raonic (5,250) and Nishikori (4,905).

Group Ivan Lendl Semi-finals Qualification Scenarios (Thursday)

• Djokovic has already won group
• Raonic-Thiem winner will qualify in second place

Group Edberg/Jarryd play concludes with all four teams in semi-final contention (see scenarios on next page). No. 2 seeds Jamie Murray and Bruno Soares are one win away from overtaking current No. 1 Pierre-Hugues Herbert and Nicolas Mahut, who hold a 175-point lead in the Emirates ATP Doubles Team Rankings. If Murray/Soares defeat No. 6 Ivan Dodig and Marcelo Melo, they will reach the semi-finals and surpass Herbert/Mahut by 25 points. The Frenchmen are 0-2 in round robin play and they could earn 200 points with a win on Friday. In the first doubles match, four-time ATP Finals champions Bob and Mike Bryan take a 2-0 head-to-head record against No. 8 Treat Huey and Max Mirnyi. The Bryans are trying to reach the semi-finals for the fourth straight year and 11th time in 14 appearances. Mahut will clinch year-end No. 1 in the individual Emirates ATP Doubles Rankings if he wins on Friday or Murray/Soares lose a match. No Frenchman has ever finished a season as World No. 1 in singles or doubles.

Group Edberg/Jarryd Semi-finals Qualification Scenarios (Thursday)

• Regardless of score, if J. MURRAY / B. SOARES defeat I. DODIG / M. MELO and B. BRYAN / M. BRYAN defeat T. HUEY / M. MIRNYI, then J. MURRAY / B. SOARES win the group and B. BRYAN / M. BRYAN qualify 2nd.
• Regardless of score, if I. DODIG / M. MELO defeat J. MURRAY / B. SOARES and T. HUEY / M. MIRNYI defeat B. BRYAN / M. BRYAN, then I. DODIG / M. MELO win the group and J. MURRAY / B. SOARES qualify 2nd.
• If J. MURRAY / B. SOARES defeat I. DODIG / M. MELO in 2 sets and T. HUEY / M. MIRNYI defeat B. BRYAN / M. BRYAN in 2 sets, then J. MURRAY / B. SOARES win the group and order of remaining teams is determined by % of games won.
• 4) If J. MURRAY / B. SOARES defeat I. DODIG / M. MELO in 2 sets and T. HUEY / M. MIRNYI defeat B. BRYAN / M. BRYAN in 3 sets, then J. MURRAY / B. SOARES win the group and B. BRYAN / M. BRYAN qualify 2nd.
• 5) If J. MURRAY / B. SOARES defeat I. DODIG / M. MELO in 3 sets and T. HUEY / M. MIRNYI defeat B. BRYAN / M. BRYAN in 2 sets, then J. MURRAY / B. SOARES win the group and I. DODIG / M. MELO qualify 2nd.
• If J. MURRAY / B. SOARES defeat I. DODIG / M. MELO in 3 sets and T. HUEY / M. MIRNYI defeat B. BRYAN / M. BRYAN in 3 sets, then J. MURRAY / B. SOARES win the group and B. BRYAN / M. BRYAN qualify 2nd.
• If I. DODIG / M. MELO defeat J. MURRAY / B. SOARES in 2 sets and B. BRYAN / M. BRYAN defeat T. HUEY / M. MIRNYI in 2 sets, then T. HUEY / M. MIRNYI are eliminated and order of remaining teams is determined by % of games won.
• If DODIG / M. MELO defeat J. MURRAY / B. SOARES in 2 sets and B. BRYAN / M. BRYAN defeat T. HUEY / M. MIRNYI in 3 sets, then I. DODIG / M. MELO win the group and J. MURRAY / B. SOARES qualify 2nd.
• If I. DODIG / M. MELO defeat J. MURRAY / B. SOARES in 3 sets and B. BRYAN / M. BRYAN defeat T. HUEY / M. MIRNYI in 2 sets, then J. MURRAY / B. SOARES win the group and B. BRYAN / M. BRYAN qualify 2nd.
• If I. DODIG / M. MELO defeat J. MURRAY / B. SOARES in 3 sets and B. BRYAN / M. BRYAN defeat T. HUEY / M. MIRNYI in 3 sets, then J. MURRAY / B. SOARES win the group and B. BRYAN / M. BRYAN qualify 2nd.

Who is going to finish the year No. 1? After four days of play at the Barclays ATP World Tour Finals, we’re not much closer to an answer.

Neither Andy Murray nor Novak Djokovic is giving each other an inch in the battle to finish No. 1 in the year-end Emirates ATP Rankings. Both have started the tournament with two round-robin victories, leaving Murray with an effective lead over the Serb of 130 points, the same edge with which he entered the tournament.

On paper Murray is 405 points ahead of Djokovic, but the Scot will see the 275 points he earned in the 2015 Davis Cup final fall from his points total on 28 November, the day the year-end rankings are calculated. So, that effectively leaves Murray with a 130-point lead at the half-way point of the season finale.

Djokovic does have one advantage over Murray: he has already clinched his place in the semi-finals. Murray has a strong claim to a semi-final spot after two strong victories over Marin Cilic and Kei Nishikori. But Stan Wawrinka’s defeat of Cilic Wednesday night means that the Scot must wait until Friday’s final-day of group play to confirm his semi-final spot.

Should Murray join Djokovic in the semi-finals, here are the key scenarios…

• If Murray and Djokovic meet in SFs, the winner of that match will clinch No. 1
• If they don’t meet in SFs, the player advancing farthest in the tournament will clinch No. 1
• If they both lose in the semi-finals, Murray will clinch No. 1 unless Djokovic has a better round-robin record

But there are several other scenarios, including one that could see Murray finish No. 1 even if he misses the semi-finals, provided Djokovic doesn’t go 3-0 in round-robin play and the Serb doesn’t reach the final. If Murray misses the semi-finals, Djokovic can clinch by going 3-0 in group play or by going 2-1 and then winning his semi-final match.

Murray is looking to become the 17^th man in history (since 1973) to finish as the year-end No. 1. Djokovic is looking to finish No. 1 for the third consecutive year, and for the fifth time overall.

Murray became World No. 1 for the first time in his career on 7 November. The last time a No. 2 dethroned the incumbent No. 1 at the season finale to claim the year-end No. 1 title was back in 2001, when Australia’s Lleyton Hewitt overtook Brazilian Gustavo Kuerten in Sydney.

For each group-stage match win at the Barclays ATP World Tour Finals, players earn 200 points. A semi-final win means an additional 400 points and a win in the final brings a further 500 points.