It’s not often that an alternate steps into the fray at the Nitto ATP Finals and has the chance to make an immediate impact. But that’s exactly the opportunity that awaits Pablo Carreno Busta on Wednesday in London.

Carreno Busta will be thrown into the cauldron under the bright lights and vibrant atmosphere at The O2, with a spot in the semi-finals still very much up for grabs. The Spaniard entered the tournament when countryman Rafael Nadal withdrew due to a right knee injury.

“I dreamt a lot of times to be here and play,” said Carreno Busta on Tuesday. “I think it’s a big opportunity for me. I will try to do my best. I think I have no pressure, nothing to lose. I will try to enjoy and to learn, and to win of course.”

The fourth alternate to feature at The O2, since the Nitto ATP Finals moved to London in 2009, Carreno Busta is bidding to become just the second to win a match there. In 2011, Janko Tipsarevic stunned fellow Serbian Novak Djokovic after replacing Andy Murray.

Alternates At The O2

Carreno Busta opens his bid to crash the semi-final party when he faces Dominic Thiem in Wednesday’s night session. There will be no secrets when the Spaniard and the Austrian square off, having met on six previous occasions in their pro careers. 

The World No. 10 took a final encounter at the ATP Challenger Tour event in Como, Italy, in 2013, but Thiem has since reeled off four straight victories at the tour-level. Their lone hard-court meeting came in the third round of the 2016 US Open, won by Thiem in four sets. The 24-year-old also prevailed in the title match of the Rio Open presented by Claro earlier this year.

Carreno Busta enters their latest encounter on the heels of a career-year on the ATP World Tour, boasting a 36-24 win-loss mark, a title on the clay of Estoril and impressive semi-final finishes at both the US Open and BNP Paribas Open. With the opportunity to add another signature moment, he knows exactly what is at stake against Thiem.

“I need to be very aggressive,” added Carreno Busta, who will also face Grigor Dimitrov on Friday. “I need to play my game, to serve good. He is very good with his forehand, and also with the backhand down the line. I need to be focused all the time, to be very positive, and fight. 

“Normally the alternates here can play the last match. But I have the opportunity to play two matches, and also to be in the semi-finals. I need to be focused on the match against Thiem. I think it will be very tough.”

With Thiem in danger of falling to 0-2 in Group Pete Sampras, the pressure will be ratcheted up. He dropped a tight opener to Grigor Dimitrov 6-3, 5-7, 7-5 on Monday, but will be bolstered by his performance against the Bulgarian and his experience advantage at the season-ending championships. The Austrian is making his second appearance in London, following a 1-2 campaign last year.

One key area to keep an eye on will be Thiem’s success against the Carreno Busta serve. He made significant in-roads on the Spaniard’s delivery in their four FedEx ATP Head2Head battles, seizing a combined 18 of 39 break chances. The fourth seed is focused on the task ahead.

“There are two more matches, two more chances,” said Thiem. “I think it’s just over when I cannot reach the semi-finals anymore, and when I also cannot calculate it any more. That’s all I think about now. I will just focus on myself and obviously try everything to win the match on Wednesday, to still have a shot for the semi-finals.”

 Watch Full Match Replays

The first doubles team to advance to the semi-finals of the Nitto ATP Finals is not the pair many would have expected.

Eighth-seeded Ryan Harrison and Michael Venus, who lost five of six matches to close their regular season, defeated Pierre-Hugues Herbert and Nicolas Mahut, 6-7(4), 6-4, 10/5, to guarantee a berth in the final four at The 02, clinching first place in Group Eltingh/Haarhuis.

Once top-seeded Henri Kontinen and John Peers — who this year’s Roland Garros champions beat on Sunday — took down Jean-Julien Rojer and Horia Tecau in the first match of the day Tuesday, Harrison and Venus simply needed a win against Herbert and Mahut.

And that’s what they got, eliminating Rojer and Tecau from semi-final contention in the process. The American-Kiwi duo evened their FedEx ATP Head2Head series with the Frenchmen at 1-1, after Herbert and Mahut got the better of them at the ATP World Tour Masters 1000 event in Cincinnati earlier this season in straight sets.

It looked like the Frenchmen might take another straight-sets victory when they cruised in the opening-set tie-break without dropping a point on serve. But Harrison and Venus did not drop their heads or their levels, bursting out of the gates to immediately break in the second set. On break point in the first game, Harrison laced a return at the net man, Mahut, eliciting a weak enough reply for Venus to swoop in and put away a volley. 

Harrison and Venus then faced 0/40 with the American serving up 3-2, but they saved all four break points. Harrison came up with a clutch jamming serve into Herbert’s body at deuce, which the Frenchman could only dump into the net. They used that momentum to close out the set and at one point win nine of 11 points in the Match Tie-break to earn their second triumph of the tournament.

Harrison and Venus will look to finish round-robin play with a perfect record against Rojer and Tecau on Thursday.

 Watch Full Match Replays

The ATP and Rolex have announced a multi-year extension of their partnership. The agreement sees Rolex continue as the Official Timekeeper of the ATP World Tour, as well as the season-ending Nitto ATP Finals at The O2 in London, through to 2020.

Rolex has a long-standing relationship with tennis, promoting precision, excellence and innovation in the sport for more than 40 years. The Swiss watch brand is a sponsor of many of the leading tournaments, and is proud to count Roger Federer, the longest-standing No.1 in the history of the sport, among its family of Testimonees.

Chris Kermode, ATP Executive Chairman & President, said: “Rolex is a brand that is steeped in the history of professional tennis. They have been a valued partner of our season-ending finale since 2005, and to the ATP World Tour since 2013, and their commitment to our sport speaks volumes. We’re delighted to extend our successful partnership.”