Canadian starlet Eugenie Bouchard admitted it was "a bit ugly" as she held off former world number one Venus Williams 7-6 (8/6), 2-6, 6-4 to reach the Family Circle Cup quarter-finals Thursday.
Bouchard, an Australian Open semi-finalist who is seeded sixth in the green claycourt WTA premier level event, saved two set points in the first-set tiebreaker, and rallied from a break down in the third to advance to a meeting with second-seeded Serbian Jelena Jankovic.
Williams followed her younger sister, world number one and top seed Serena, out of the tournament.
Venus Williams, who won the Charleston title in 2004, held two set points at 6-4 in the first-set tiebreaker, but 20-year-old Bouchard won four successive points to take the set.
Williams bounced back with a strong second set and broke for a 2-1 lead in the third, but her unforced errors allowed Bouchard to get back in it and the Canadian broke her in the final game to seal the win.
"In the second set she really started going for her shots," Bouchard said.
"I just tried to keep fighting. It was a little bit ugly at times, but I just kept trying to fight through it."
Jankovic defeated big-hitting Croatian Ajla Tomljanovic 7-5, 6-1 to set up a meeting with Bouchard.
Tomljanovic, who had saved a match point in her first two matches this week, pushed Jankovic with a powerful baseline game in the opening set.
Trailing 5-3, the Croatian saved three set points before surrendering the opening set. From there, however, Jankovic cruised.
"My opponent was very aggressive today. That's the way she plays," Jankovic said. "I had to stay low and try to get my stride as well. I'm glad I was able to stay strong in that first set."
Third-seeded Sara Errani of Italy advanced with a narrow 7-6 (8/6), 7-6 (7/5) victory over China's Peng Shuai.
Peng had a set point in each set but couldn't convert.
Errani will face Swiss qualifier Belinda Bencic, a 6-7 (4/7), 6-4, 6-1 winner over Ukrainian Elina Svitolina in a battle of teenagers.
Fourth-seeded Sabine Lisicki was a third-round casualty, falling to fellow German Andrea Petkovic 6-1, 6-0.
Petkovic next faces ninth-seeded Czech Lucie Safarova, who upset seventh-seeded Australian Samantha Stosur 3-6, 6-4, 6-4.
Jana Cepelova followed up her big win over Serena Williams with a 7-6 (7/4), 3-6, 6-3 victory over 13th-seeded Russian Elena Vesnina.
Cepelova will face fellow Slovakian Daniela Hantuchova in the quarter-finals. Hantuchova breezed past Teliana Pereira of Brazil 6-2, 6-3