(Adds detail, Benneteau quote)
PARIS May 31 (Reuters) - Roger Federer's French Open campaign gathered momentum as the Swiss second seed eased past France's Julien Benneteau 6-3 6-4 7-5 to reach the fourth round in awe-inspiring fashion on Friday.
There was the usual array of running aerial forehands, gravity-defying drop shots and whipped backhands from the former world number one who booked a meeting with American Sam Querrey, the 18th seed, or French 15th seed Gilles Simon.
It was Federer's 57th win at Roland Garros and the Swiss is now one shy of Guillermo Vilas and Nicola Pietrangeli's joint record.
Benneteau, the 30th seed, broke in the first game to open a 2-0 lead but 17-times grand slam champion Federer kept his cool and turned the situation around in no time.
Benneteau, who has been struggling with a groin problem, bowed out on the first match point when he could not retrieve another powerful Federer forehand.
"I thought it was a different match than what we usually play against each other. He was clearly handicapped with the leg, which I was able to take advantage of," Federer told a news conference.
"I kind of knew I had always a cushion."
Benneteau admitted he had not been in peak condition.
"I felt I was not at the best level given all the efforts I made during the first two matches," he said. "And also the pain that I have.
"And due to this I was not 100 per cent present, physically speaking, which means that it was getting tougher and tougher on the court."
Federer, one of the Paris crowd's favourites, left Court Philippe Chatrier to a standing ovation.
"You are so nice to me," Federer said courtside.
Benneteau started with an exquisite crosscourt forehand winner and took the first game on Federer's serve but the Frenchman, who beat the Swiss in Rotterdam this year, could not sustain the pace.
At 3-3, Federer upped the tempo, winning 14 points in a row to snatch the opening set and he started the second in convincing style with some jaw-dropping shots.
The second game of the second set lasted just 45 seconds and Federer flicked a sublime backhand into Benneteau's feet to break decisively in the ninth game.
Benneteau continued to fight in the third, but Federer, who won the title in Paris in 2009, was simply too good.
He has now dropped 23 games over three straight-set victories.
"I'm happy because I have not used much of my energy so far," said Federer.
"I feel totally relaxed. Mentally I'm okay. I'm quite confident. I can feel it, which is what you need to be if you want to go deep and have good results here at Roland Garros."
(Editing by Ed Osmond)