Top seed Marion Bartoli survived a struggle lasting for more than three hours, with the Frenchwoman overcoming a massive 18 double-faults to advance at the WTA hardcourt event on Wednesday.

Bartoli defeated American Vania King 6-4 5-7 6-4 in an error-plagued marathon to reach the quarter-finals after a bye in the first round.

“It’s a very hard surface,” Bartoli said. “Playing three hours is not really helping, but I think it was a great fight from both of us and we tried our best.”

Bartoli, who will not play in the London Olympics due to a longstanding dispute with the French tennis federation, won a battle in which both women took lengthy injury breaks, with Bartoli going off court for treatment in the third set.

Bartoli said she felt her hip hurting since the first set.

“I really tried to keep the pain away and tried to not think about it,” she said.

“Obviously, it came to a point where I had really a lot of problems serving. I really needed some help from the trainer.”

Bartoli advanced despite losing serve eight times against the world No.59 King.

The French player lost serve in the opening game of the final set but fought to get it back as she broke for 4-4 before closing out the match at La Costa on a concluding break.

US Olympian Varvara Lepchenko upset South African eighth seed Chanelle Scheepers 6-4 6-2 to reach her third quarter-final of the season.

The 44th-ranked Lepchenko will join Venus and Serena Williams plus fellow Carlsbad competitor Christina McHale on a flight to London next week for the Olympic tennis event.

Lepchenko reached quarter-finals this season indoors in Memphis in February and on the blue clay of May’s Madrid Masters, where she lost to Agnieszka Radwanska.

The American broke Scheepers three times and advanced as the South African sailed a return long.

“I’m still improving and still trying to prove to myself out there that I can play on all the surfaces,” said Lepchenko. “A lot of people put me into a certain category. But I feel I can play on all surfaces, and I’ve been showing it.”

Lepchenko next takes on fourth seed Nadia Petrova, who beat American Alexa Glatch 6-4 6-3.

Taiwanese qualifier Chan Yung-Jan beat Britain’s Heather Watson 6-3 7-6 (7-2).

Chan, ranked 161st, will face a Friday test against fourth seed Jelena Jankovic, the former world No.1 Serb, or Hungarian Melinda Czink.