Defending champion Novak Djokovic won his 19th match in a row to join Rafael Nadal in qualifying for the semi-finals of the Barclays ATP World Tour Finals at the O2 Arena in London.
The Serbian saw his hopes of finishing the year as World No 1 ended by Nadal’s win over Stanislas Wawrinka on Wednesday but responded in style to beat Juan Martin del Potro 6-3 3-6 6-3.
Djokovic had to dig very deep at the start of the third set but his confidence is high at the moment and he guaranteed he will top Group B while Del Potro and Roger Federer will fight it out for second spot.
Earlier, Federer bounced back from his opening defeat by Djokovic to beat Richard Gasquet 6-4 6-3.
The night match was a meeting between the two form players of the autumn.
Since the US Open, Djokovic and Del Potro had won 34 matches between them and five titles and their meeting in London in the Wimbledon semi-finals was one of the matches of the season.
Djokovic won that one, as he had six of their previous seven meetings, and it was the second seed who dominated the first set once he saved two break points in the opening game.
Del Potro withstood three break points in the fourth game and one more in the sixth but, on his fifth chance, Djokovic sent his opponent scampering from corner to corner before eventually the Argentinian could resist no longer.
Djokovic was as good on serve as he was off the ground and he clinched the set with a second-serve ace.
Del Potro was simply not managing to dictate enough of the points but in the second set he stepped into the court more and got his reward, albeit with a big slice of luck as the ball dropped off the top of the net to give him a 4-2 lead.
Soon after it was one set all and it was Del Potro who was on top going into the decider.
His big chance arrived with two break points in the third game but a forehand error cost him dearly and three games later he cracked as Djokovic broke to love.
The World No 2 has rediscovered the surety in crunch moments of matches and he was rock solid as he served out the win to love.
Federer, meanwhile, was happy to admit his win over Gasquet was much needed but the doubts about his game remain.
There was some sparkling touch play from the Swiss against a player he had beaten in 10 of their previous 12 meetings but also a lot of errors.
Federer said: “The movement, the coordination, is not exactly how I want it to be.
“Sometimes I’m in two minds but that’s where I think today was, just a battle for myself, making sure I move the right way, I play the right way, I have the right shot selection. Maybe also just getting used to the conditions a little bit.
“Richard does a good job of making you feel uncomfortable at the same time as well because he uses height and spins really well. He likes extended rallies I’m trying to force the issue.
“But those are the kind of matches I need right now straight sets against a good player. It clearly comes at the right time.”
Gasquet qualified for the tournament for the first time since 2007 but his hopes of making the semi-finals are now over.
He backed Federer to go all the way, saying: “I think it’s a great court for him. To play him indoors is very difficult for my game.
“He’s playing fast, especially with the forehand. He’s still a very good player. He’s still able to win the tournament.”