LONDON - Kei Nishikori faces a nervous wait to see if he will qualify for the semi-finals of the ATP Tour Finals after finishing his Group B campaign with a 4-6, 6-4, 6-1 victory over David Ferrer on Thursday.

Nishikori discovered just before his match was due to start that he would face Ferrer instead of his scheduled opponent Milos Raonic after the Canadian pulled out with a torn quad. But the Japanese star wasn’t fazed by that late switch and he recovered from a set down to secure his second win on his debut appearance in the season-ending tournament at London’s O2 Arena. His fate is now in the hands of Roger Federer, who is already through to the last four and can seal Nishikori’s place as group runner-up if he beats Andy Murray later on Thursday.

US Open finalist Nishikori, who saw off Ferrer with 41 winners in just under two hours on court, would also qualify in second place if Murray beats Federer in three sets, but he will be eliminated if the Scot wins in straight sets. “The third set was almost perfect. I served well and everything worked well,” Nishikori said. “It was really difficult to make this adjustment (to face Ferrer). They told me one hour before the match. “It was tough to change tactics but I’d prepared well and I’m happy to win.”

World number 10 Ferrer, who had been practising at the O2 Arena all week in case of injury withdrawals, was well-compensated for his brief role, making $85,000 for being an alternate as well as a $155,000 appearance fee. “Last week I was on holidays but I came here Sunday and practised four days so I was in perfect condition. Kei was just better today,” Ferrer said. Although Nishikori was initially perturbed by Ferrer’s presence, he knew he had won all three of their previous meetings this year, including from a set and 5-2 down at the recent Paris Masters.

He had the first break point in the fifth game, but Ferrer was able to battle his way to a hold. It seemed that would be only a minor inconvenience when Nishikori earned a break point with a brilliant volley and converted it with a superb forehand cross-court winner for a 4-3 lead. But, with the set in his grasp, Nishikori suddenly lost his rhythm and Ferrer broke back before capitalising on another sloppy service game to take the set when the Japanese player netted an overhead shot.

Nishikori’s response was emphatic and he broke Ferrer in the first game of a second set which he won in comfortable fashion. For the first time in nine matches at this year’s event, a final set was necessary and that benefitted Nishikori, who had won 20 of 22 deciding sets in 2014. Nishikori has been struggling with a right wrist problem this week and looked in discomfort as he grimaced at times between points. But he battled on and landed the knock-out blow with a double break in the first and third games to seal the win.

DJOKOVIC EYES TOP SPOT AFTER WAWRINKA ROUT: Novak Djokovic moved within touching distance of ending the year as the world number one after crushing Stan Wawrinka 6-3, 6-0 at the ATP Tour Finals. Djokovic needs to win all three of his Group A matches to ensure he will hold off Roger Federer in the race for first place and the Serb secured the second of those victories with a ruthless 65-minute rout at London’s O2 Arena.

The reigning Wimbledon champion will be guaranteed top spot if he beats Tomas Berdych on Friday in a match he also has to win to be certain of making the last four at the prestigious season-ending event. Wawrinka’s loss means the Swiss world number four needs to defeat US Open winner Marin Cilic, thrashed 6-3, 6-1 by Berdych earlier on Wednesday, to have a chance of making the last four.

After demolishing Cilic for the loss of two games on Monday, Djokovic has lost only five games during his first two matches. Djokovic has won his last 29 indoor matches, including 12 in a row at the Tour Finals, and he remains on course to become the first player since Ivan Lendl in the 1980s to win the Tour Finals three years in a row.