The Swiss former world no.1 dominated of the first set and in front of a jam packed Philippe Chartier stadium, he broke Mahut in the sixth game before closing out the set and taking a lead in the match.
But the Wimledon record man Mahut (he lost to Isner in the memorable five set match 70-68 in the fifth) fought back in the second set, and taking Federer’s in the 10th game, he levelled the match at 1 set all.
Federer hasn’t really shown his best yet at this year’s Roland Garros, but the big difference between now and about 6 months ago is that he is winning matches even if not on top form.
The Swiss maestro regained momentum and restored order after taking the third set with ease. He managed to reduce his unforced errors and looked once again invincible on his serve.
Despite the French crowd’s love for Federer, they were eager to see the match go the distance. But the Swiss destroyed their dream and after both players exchanged one break each to get to 5-5, the Swiss struck again, taking Mahut’s serve for the second time in the set before serving out the match with confidence.
Federer’s next opponent will be Belgian lucky loser David Goffin, who surprisingly overcame Poland’s Lukasz Kubot, beating him 7-6 (4) 7-5 6-1.
Also through to the next round is the Argentine Juan Martin del Potro, who eliminated Marin Cilic of Croatia in straight sets 6-3 7-6 (7) 6-1 in 2 hours and 32 minutes.
The 9th seed Del Potro, who has won six out of eight previous meetings against Cilic, moved across the court like a tiger, despite his knee being strapped up. He cruised past the first set and took a quick 5-2 lead in the second, just before Cilic managed to recover and levelled it at 5-5. As the set went into a breaker, the Argentine regained his focus once again and gave himself an almost invincible two set lead.
Cilic showed his frustration as Delpo made quick work of him in the third set, racing to a 6-1 win.
Del Potro’s next opponent will be the 7th seed Czech Tomas Berdych, who eliminated Kevin Anderson of South Africa.