Federer lost in the semifinals of last year's U.S. Open and this year's Australian Open to Djokovic, who has won 43 matches in a row.
A year ago at Roland Garros, Federer exited in the quarterfinals, ending his streak of reaching the semifinals at a record 23 consecutive Grand Slam tournaments.
Druing this year's French Open, the third-seeded Federer hasn't dropped a set. He started slowly against Monfils, getting broken at love to fall behind 3-1, before taking control.
Monfils was the last Frenchman in the field of 21 who entered. He's now lost to Federer at the French Open in three of the past four years.