Ashleigh Barty beats doubles partner CoCo Vandeweghe in Tokyo

Australian No.1 Ashleigh Barty overcame doubles partner CoCo Vandeweghe in a tough three-set encounter to progress to the second round at the WTA Tokyo tournament.

Barty, the seventh seed, had to battle all the way in a 4-6 6-3 7-5 win over American Vandeweghe, her partner earlier this month in her first grand slam doubles triumph at the US Open.

Australia's world No.17 will play either former Australian Open champion Victoria Azarenka or Japanese wildcard Kurumi Nara in the second round.

If she's to go deeper into the tournament Barty will then have to potentially overcome world No.2 Caroline Wozniacki with US Open champion Naomi Osaka looming large in a semi-final.

In other matches fifth-seeded Sloane Stephens was eliminated from the first round by Donna Vekic 6-4 6-4.

The 2017 US Open champion had also lost to the unseeded Croat in the first round at Wimbledon.

Also No. 8 Barbora Strycova defeated Zarina Diyas 6-4 6-4.

In other matches, Johanna Konta downed Gabriela Dabrowski 6-2 6-0 and Alison Riske beat Eugenie Bouchard 6-4 6-4.

Wozniacki is the top-seeded player at the tournament and Caroline Garcia is No. 2. Both had byes in the first round.

Third-seeded Osaka also had a bye and plays Wednesday against Dominika Cibulkova.