Serena Williams wince through a sprained ankle and a first-set wobble to beat Slovenia's Katarina Srebotnik 4-6, 6-4, 6-3 and reach the Family Circle Cup quarter-finals on Thursday.
The fifth-seeded American won the last eight points to set up a clash with Russian number two seed Maria Sharapova, who defeated Ukrainian Tatiana Perebiynis 7-5, 6-2.
"I'll tell you how I feel [on Friday], seeing that I fell and I'll see how I feel," Williams told reporters. "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, winning their third-round match 6-0, 6-2 in 52 minutes.
Russia's fourth-seeded Elena Dementieva and ninth seed Vera Zvonareva of Russia, seventh-seeded Patty Schnyder of Switzerland, 10th seed Agnes Szavay of Hungary and unseeded Alize Cornet of France also advanced to the last eight.
Sharapova won her first career claycourt title on Sunday by beating Dominika Cibulkova at Amelia Island.
The Russian, who reached the quarter-finals despite double-faulting to give Perebiynis a set point in the first set, has a 2-4 win-loss record against Williams.
"Both of us like to go for the big shots," Sharapova said. "And I think considering that this clay is a little faster than normal clay, I think it suits both our games pretty well and hopefully will produce some good tennis."
With the Williams and Sharapova matches on the stadium court, Jankovic was relegated to the outer Althea Gibson Club Court.
"I didn't like it, to be honest. I prefer center 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."