Stosur into 2nd round at Tokyo tennis open

Australian tennis player Samantha Stosur has beaten Alison Riske in the opening round of the Tokyo Open.

Australian Samantha Stosur has beaten Alison Riske in the opening round of the Tokyo Open. (AAP)

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.