PARIS -- Roger Federer came back from a two-set deficit for the seventh time in his career and beat Juan Martin del Potro 3-6, 6-7 (4), 6-2, 6-0, 6-3 at the French Open on Tuesday to reach his record-tying 31st Grand Slam semifinal.

Federer already owns 16 major titles, including at Roland Garros in 2009, but has gone more than two years without adding to that record total.

Del Potro, whose only Grand Slam title came by beating Federer in the 2009 U.S. Open final, was bothered by his heavily wrapped left knee Tuesday.

Federer got better and better as the match progressed. He was pretty much perfect in the fourth set, with 13 winners and zero unforced errors.

Del Potro, whose only Grand Slam title came by beating Federer in the 2009 U.S. Open final, was bothered by his heavily wrapped left knee Tuesday.

Federer got better and better as the match progressed. He was pretty much perfect in the fourth set, with 13 winners and zero unforced errors.