US OPEN 2019
Czech sixth seed Petra Kvitova is out of the US Open after losing 6-4 6-4 to world number 88 Andrea Petkovic in the second round.
The two-time Wimbledon champion, who has been struggling with a forearm injury, was broken in the 10th game as the German, 31, took the opening set.
She was a break up in the second set before Petkovic broke twice more en route to sealing victory.
Japanese defending champion Naomi Osaka defeated Pole Magda Linette 6-2 6-4.
Linette, the world number 53, was 3-0 up in the second set before the world number one fought back.
Osaka could face promising 15-year-old Coco Gauff next, with the American playing Hungary’s Timea Babos in her second-round match from 00:00 BST on Louis Armstrong Stadium.
Petkovic will now play either Belgian Elise Mertens or Kristyna Pliskova.
Elsewhere, Ukrainian 32nd seed Dayana Yastremska beat Swede Rebecca Peterson 6-4 6-1 to set up a third-round meeting with compatriot and fifth seed Elina Svitolina.