PARIS—Gael Monfils, who has beaten Roger Federer the last two times they’ve met—both matches on clay, this year in Monte Carlo and in last year’s Davis Cup final—believes the key to his wins over the Swiss was getting him out of his “comfort zone.” The Frenchman will meet Federer in the fourth round of Roland Garros. Federer is 8-4 lifetime against Monfils, including a win at the 2014 U.S. Open where he came from two sets down and saved match points.

“Some matches Roger kill me,” Monfils said of his recent wins. “Somehow I just maybe find a couple stuff, in my game, to put him in trouble and to actually move him—I think Roger is very comfortable on couple of shots or couple area that I try to manage to put him out of this comfort zone. And then also I try to find a rhythm also with Roger that I'm happy with, because Roger always wants to dictate the match the way he wants, the way he make you wait or speed up the match, the way he will select his shot.”

Monfils has lost to Federer three times at Roland Garros, in 2008, 2009 and 2011. He won only one set in those matches, during the 2008 semifinal.

The No. 13 seed, who has never reached the final of a Grand Slam tournament, enjoys playing in front of French crowds and thinks he has improved against Federer. “I really try to change out of him, and sometime Roger get pissed a little bit,” Monfils said. “And also, whether I will—and I know he will respect it, but when he's good—actually, when I saw it the most it was in U.S. Open, you know, Roger was very unhappy when the crowd is not behind him. And that will help me a lot, for sure.”