Angelique Kerber knocked out by Anett Kontaveit in Cincinnati
Estonian Anett Kontaveit 13th German seed expelled Angelique Kerber 7-6 (7), 6-2 in the first round of the Cincinnati Masters on Tuesday.
Kontaveit, 23, fell 5-3 and saved a set point at 6-5 on the way to take the first set against the former world number one.
He broke Kerber twice to win the second set, winning the first nine points, and two holds to love gave him a 4-0 lead.
Swiss number 12, Belinda Bencic, retired with a foot injury after beating former world number one Victoria Azarenka of Belarus 6-4, 1-0.
Ekaterina Alexandrova of Russia, Zheng Saisai of China and Donna Vekic of Croatia were some of the first winners.
Alexandrova returned to Carla Suárez 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 6-4, 6- 3 winner over Czech Katerina Siniakova.