Eighth-seeded Sloane Stephens advanced to the Hobart International semifinals Thursday with a 6-3, 4-6, 7-5 win over fellow American and qualifier Lauren Davis.

Stephens will play Elena Vesnina of Russia in one of Friday's semifinals. Vesnina played better in windy conditions Thursday to beat wild-card Jarmila Gajdosova of Australia 6-3, 6-2.

"I had to be smart and in the wind you have to use it like a weapon," Vesnina said.

Ninth-seeded Mona Barthel of Germany beat Tsvetana Pironkova of Bulgaria 6-3, 6-3 and will play the winner of Thursday's night quarterfinal between Monica Niculescu of Romania and Kirsten Flipkens of Belgium.

The 22-year-old Barthel said she's "improved a lot" as she begins her second season on the WTA Tour.

"I feel like I learned so much last year, playing all these tournaments and playing against the top players," Barthel said. "My serve has got better and I feel like my groundstrokes are better ... but maybe a little more confidence this year."

The final is scheduled for Saturday at the Domain Tennis Centre.