Venus Williams advanced at the Family Circle Cup on Wednesay, battling from behind to defeat Chanelle Scheepers 7-5, 7-5.
It was another long day Wednesday for Williams, ranked No. 28 in the world and who needed an hour and 50 minutes to finish the straight-set victory over the South African. Williams fell behind 3-1 in the first set and trailed 4-1 in the second.
The seven-time Grand Slam champion has battled injuries and Sjogren's syndrome, a fatigue-causing autoimmune disease, during the past two years. She was on the green clay in Charleston for two hours and 15 minutes on Tuesday in a three-set victory.
She'll next face the sixth seed, Eugenie Bouchard of Montreal. They've met just once before, with the American winning in three sets in Tokyo in 2013.
American Sloane Stephens was upset 6-4, 6-4 by Elina Svitolina at the Family Circle Cup, losing to the 35th-ranked Ukrainian on Wednesday.
The 18th-ranked Stephens fell to the 19-year-old Svitolina, who earned her fourth career victory over a top 20 player — the third coming last week at the tournament near Miami.
The 21-year-old Stephens gave credit to her opponent, who moved up seven spots to reach a career-high ranking this week.
"She played pretty well, and it's just unfortunate that I lost, but I mean, you can just learn from the mistakes and things like that and build on it," Stephens said.
Last week at the Sony Open, Svitolina defeated Bethanie Mattek-Sands, Bouchard and Barbora Zahlavova Strycova before losing to No. 3 Agnieszka Radwanska.
"I started to believe more in myself that I can compete with players like this, top level, top 20 and top 10," said Svitolina, who is making her first appearance on the green clay in Charleston. "I think this is the key, that I believe more in myself and I play more solid from the baseline and trying to go forward to finish the point earlier."
Second-seeded Jelena Jankovic, the highest seeded player remaining after top-ranked Serena Williams was upset Tuesday, plays Wednesday night against American Lauren Davis.
Stephens says she's looking forward to a long career.
"If I play 10 more years of tennis, until I'm 31, that's a lot of tennis to be played," Stephens said. "I could win the next Grand Slam or I could win one in six years and that would still be, you know, if I had pretty decent results and I was pretty consistent, I think that would still be pretty good."
In other matches, Daniela Hantuchova of Slovakia defeated American qualifier Grace Min 6-2, 6-3 while Elena Vesnina of Russia stopped Petra Cetkovska of the Czech Republic, 3-6, 6-2, 6-4.
Italian Sara Errani, ranked No. 11 in the world and seeded third, advanced as well. She won the first set 6-3 when qualifier Kiki Bertens of the Netherlands retired. Fourth-seeded Sabine Lisicki of Germany was extended to three sets before defeating American Vania King 7-5, 4-6, 6-3.
Lisicki will play fellow German Andrea Petkovic. The 14th seed, Petkovic defeated Lourdes Dominguez Lino of Spain 6-0, 6-0 while Shuai Peng of China eliminated 15th-seeded Madison Keys of the United States 6-1, 6-7 (3) and 7-6 (4). Qualifier Belinda Bencic of Switzerland defeated Marina Erakovic of New Zealand 6-2, 6-1.