(Reuters) - Estonian Anett Kontaveit ousted German 13th seed Angelique Kerber 7-6(7) 6-2 in the opening round of the Cincinnati Masters on Tuesday.
The 23-year-old Kontaveit came from 5-3 down and saved a set point at 6-5 on the way to taking the opening set against the former world number one.
She broke Kerber twice to win the second set, winning the first nine points, and two holds to love gave her a 4-0 lead.
Swiss 12th seed Belinda Bencic retired with a foot injury after trailing former world number one Victoria Azarenka of Belarus 6-4 1-0.
Russia’s Ekaterina Alexandrova, Zheng Saisai of China and Croatia’s Donna Vekic were among other early winners.
Alexandrova turned back Carla Suarez Navarro of Spain 6-4 6-1, Zheng beat Viktoria Kuzmova of Slovakia 6-3 6-1 and Vekic, who will face Azarenka in the second round, was a 6-4 6-3 winner over Czech Katerina Siniakova.
Serena Williams is scheduled to play a night match in her first tournament since withdrawing from the Rogers Cup final in Toronto on Sunday due to back spasms.
The 10th-seeded American will face Kazakh Zarina Diyas.
Reporting by Gene Cherry in Raleigh, North Carolina, editing by Ed Osmond