PARIS — Serena Williams rallied to reach the fourth round of the French Open on Saturday, beating Maria Jose Martinez Sanchez of Spain 4-6, 6-3, 6-4.

The second-seeded Williams seemed to have trouble dealing with her opponent's serve-and-volley tactics, and piled up plenty of unforced errors. But she managed to avoid the fate of her sister Venus, who lost on Friday. Both lost in the third round last year.

Williams also struggled in the first round, but she easily advanced from the second after losing only two games.