PARIS — Roger Federer and Gael Monfils know each other — and each other's games — quite well.
Their fourth-round match Sunday will be their 13th meeting overall (Federer leads 8-4) and fourth at the French Open (Federer leads 3-0).
"Roger asks many questions," the 13th-seeded Monfils said, "and I have to find many answers."
Monfils has won their most recent two matches, both on clay, and both in straight sets.
"He's played me tough throughout my career," Federer said. "Especially the last four, five years now, he's been tougher for me to play against.