Roger Federer of Switzerland hits a return during his men's singles tennis match against Richard Gasquet of France at the ATP World Tour Finals at the O2 Arena in London November 7, 2013. [Photo/Agencies]

LONDON - A razor-sharp Roger Federer got back to winning ways at the ATP World Tour Finals with a 6-4 6-3 defeat of Frenchman Richard Gasquet on Thursday to keep alive his last-four chances.

Under pressure after losing to title favourite Novak Djokovic in his opening Group B match, the six-times former champion looked much more like his old, majestic self as he extended his career record over Gasquet to 11-2.

There were still the kind of lapses that have hampered the Swiss during a fallow season and nerves at the end when Gasquet saved five match points but Federer wrapped up victory and will face Juan Martin del Potro on Saturday with high hopes.

"I guess those are the kind of matches I need right now. You know, straight sets against a good player. It clearly came at the right time right now," Federer, who has only one title this year but collected the Arthur Ashe Humanitarian of the Year award, as well as the ATP fans' favourite and Stefan Edberg Sportsmanship award this week, told reporters.

"Richard has an incredible playing style and is a dangerous shot-maker," Federer, who qualified for the year-ending showdown for the 12th consecutive year, said on court.

"There was pressure after losing my first one. It was a big win for me and I hope now to keep it up against Juan Martin."

Federer played with far more authority than he did against Djokovic and believes his victory over del Potro in the quarter-finals of the Paris Masters was an important one.

"That win for me in Paris psychologically was very important," he said. "It showed I could beat top 10 guys, I beat Richard, I beat Juan Martin last week."

Straight shoot-out

Should Del Potro lose to defending champion Djokovic in Thursday's late match, Federer's meeting with the Argentine would effectively become a straight shoot-out for a semi-final spot - a scenario Federer said he would prefer.

"That would certainly make things clearer, otherwise the arithmetic gets complicated like it did here in 2009 when nobody knew who was going through."

Despite losing the opening six points of the match, 17-times grand-slam champion Federer quickly found his stride and forged ahead with the first break in the third game when Gasquet misfired a forehand into the net.

Treating the large Swiss contingent in the sell-out crowd to some silky drop shots and his usual array of flowing passes, the 32-year-old world number seven toyed with Gasquet at times yet lost his focus when the Frenchman hit back to level at 4-4.

Gasquet was quickly put back in his place as Federer broke again to lead 5-4 and served out the set.

Gasquet, who also lost his opening match to Del Potro, surrendered his serve at the start of the second set as the high-tempo match threatened to race away from him.

To his credit, the U.S. Open semi-finalist began to assert himself and Federer had to dig himself out of trouble in three successive service games as Gasquet began to unload some ferocious backhands.

Gasquet looked poised to level at 4-4 when a blistering return had Federer scrabbling at the baseline but he could only watch in admiration as a backhand top-spin lob arched over him as yet another break point went begging.

That proved to be his last chance as Federer pounced in the following game, breaking some dogged French resistance to convert his sixth match point.