Sam Stosur is into the second round of the WTA Tokyo Open tennis tournament after beating Alison Riske 4-6 6-1 6-3 on Tuesday.

The world No.22 Stosur saved eight break points against the world No.51 Riske, with the match lasting just less than two hours.

Stosur will play eighth-seed Belinda Bencic in the second round, after she beat qualifier Xu Yi-Fan 6-0 6-0 in 43 minutes.

Daria Gavrilova lost her first-round match in straight sets, 6-2 6-2, against fifth-seed Angelique Kerber.

World No.13 Agnieszka Radwanska beat Coco Vandeweghe 6-3 6-3 to set up a second-round match against Elina Svitolina, who beat qualifier Olga Savchuk 6-2, 6-0.