LONDON (AFP) - Jo-Wilfried Tsonga remains in the hunt for a place in the semi-finals of the ATP World Tour Finals after the French sixth seed defeated America's Mardy Fish 7-6 (7/4), 6-1 on Tuesday. Tsonga, who lost his opening Group B match against Roger Federer, still has to beat Rafael Nadal in his final fixture on Thursday to have a chance of advancing, while Fish faces an early exit from the season finale at London's O2 Arena. The result also means defending champion Federer will be guaranteed a semi-final spot if he defeats Nadal in tonight's match. "It's good to win here for the first time and of course it's good for my confidence because now I will play a match to qualify for the semi-finals," Tsonga said. Tsonga believes he has more chance than usual of a shock win over Nadal because the match is on the Spaniard's least favoured hard courts. "It's better for me than to play him on clay. Last time I played him on clay it was really difficult, but this time I think I will have some chances," Tsonga said. Tsonga started in aggressive mood, earning three break points before finally breaking at the fourth attempt with a brilliant winner on the run. The 26-year-old had out-lasted Fish to claim a five-set victory in their only previous meeting, in the US Open fourth round earlier this year, and this was another rollercoaster clash. Fish broke straight back in the next game, only for the American eighth seed to surrender his own serve again to give Tsonga a 2-1 lead. Tsonga became the first player to hold serve in the next game, but the often-erratic Frenchman crumbled when he served for the set. Fish had an animated discussion with the umpire between games and letting off some steam seemed to do him good. He knocked Tsonga out of his stride with a magnificent top spin lob and levelled the score on his second break point when the sixth seed sent a backhand long. It needed a tie-break to decide the set and Tsonga took it with a pair of big serves to take advantage of his mini-break.