Seven-time Grand Slam champion Venus Williams will have to wait for a 50th career WTA title after bowing out in the third round of the claycourt tournament in Charleston on Thursday.

Williams, the third seed, had put together back-to-back wins for the first time since lifting her 49th title in Taiwan in February, but was toppled 7-6 (7/5), 2-6, 6-4 by Kazakhstan's Yulia Putintseva.

The 35-year-old American joined second-seeded Swiss Belinda Bencic, fourth-seeded Lucie Safarova and sixth-seeded Andrea Petkovic out of the tournament.

But top-seeded Angelique Kerber, the reigning Australian Open champion, powered into the quarter-finals with a 6-2, 6-3 victory over qualifier Kristina Kucova.

Kerber fired 35 winners and converted seven of her 10 break point chances, staying steady in difficult, windy conditions.

"It was a really tricky match," she said. "It was really windy and it was a completely different condition than before. I played two days ago in the night session and it was windy, cold."

"I'm really happy to win the match," added Kerber, who said she was feeling at home on the green clay of Charleston, South Carolina.

Kerber next faces Romanian Irina-Camelia Begu, who saved a match point en route to a 1-6, 6-2, 7-6 (7/4) victory over Puerto Rico's Monica Puig.

Russian Elena Vesnina, who ousted Bencic in the second round, reached the quarter-finals with a 6-1, 6-3 victory over Spain's Lourdes Dominguez.

Vesnina next plays Germany's Laura Siegemund, who followed up her second-round win over eighth-seeded Madison Keys with a 7-5, 6-2 victory over Croatia's Mirjana Lucic-Baroni.

Fifth-seeded Italian Sara Errani advanced to a meeting with Putintseva, downing Australian Samantha Stosur 6-4, 7-6 (7/5).

Seventh-seeded Sloane Stephens of the United States defeated Aussie Daria Gavrilova 6-4, 6-3 to book a meeting with Russian Daria Kasatkina, a 6-0, 6-4 winner over American Louisa Chirico.
Source: AFP