Serena Williams winced through a sprained ankle and a first-set wobble to beat Slovenia's Katarina Srebotnik 4-6 6-4 6-3 and reach the quarter-finals of the WTA Charleston on Thursday.

The fifth-seeded American won the last eight points to setup a clash with Russia's number two seed Maria Sharapova, who defeated Ukrainian Tatiana Perebiynis 7-5 6-2.

Asked about her injury, Williams told reporters: "I'll tell you how I feel (on Friday), seeing that I fell and I'll see how I feel. When you're playing and with the adrenaline, you can't really assess yourself."

Williams blasted 11 aces and converted four of nine break-point opportunities in the two-hour, 13-minute match against 12th-seeded Srebotnik.

Top seed and holder Jelena Jankovic of Serbia made quick work of Russian Anastasia Rodionova to win 6-0 6-2 after 52 minutes in her third round match.

Russia's fourth-seeded Elena Dementieva and ninth seed Vera Zvonareva of Russia, 10th-seeded Agnes Szavay of Hungary and unseeded Alize Cornet of France also advanced to the last eight.

Sharapova, who won her first career clay court title on Sunday by beating Dominika Cibulkova at Amelia Island, had opened play on Wednesday with a 6-0 6-0 second-round victory over American Bethanie Mattek.

The Russian, who later advanced to the quarter-finals despite double-faulting to give Perebiynis a set point in the first set, has a 2-4 win-loss career record against Williams.

With the Williams and Sharapova matches on the stadium court, Jankovic was relegated to the Althea Gibson Club Court.

"I didn't like it, to be honest. I prefer centre court," she said. "But for me it doesn't matter. Even if I'm in the parking lot or in a forest or wherever I play, I'll still go out there and play my game."

Reuters