Six-time U.S. Open champion Serena Williams defeated No. 22 Petra Martic of Croatia in straight sets (6-3, 6-4) on Sunday to advance to the tournament's quarterfinals for the 16th time in her career.
Martic, 28, made her mark on the match early, winning five straight points in the first set and breaking Williams after she had a 40-0 lead in the first game. Williams, seeded No. 8, bounced back by erasing three game points and breaking for 1-1. She jumped to a 5-3 lead before clinching the first set with a deft drop shot.
Williams then overcame a rolled right ankle which required a medical timeout to notch the victory in the second set after an hour and a half of play.