Marion Bartoli of France.

Carlsbad, California – French top seed Marion Bartoli held off a spirited challenge from young American Christina McHale to move into the semi-finals of the WTA Carlsbad event with a 7-5, 4-6, 6-4 win on Friday.

Bartoli, who will not be playing the London Olympics, competed with a thigh strapping after suffering an injury in her match the day before.

She cut down her double-faults from a massive 18 the previous night to 11 against fifth seed McHale, who beat her at the US Open last summer.

“I really don't know why it's happening,” she said of the faulty serve. “But it's hurting my whole motion. Maybe I'm not jumping as high as I'm able to do when I'm on my best.

“When you're going through those kind of patches you have to find a way somehow, that's obviously a good sign for me.”

The French number one accounted for her second straight American victim as she beat McHale in a struggle lasting almost three hours. She ousted Vania King 24 hours earlier to start her week in southern California.

Bartoli has achieved her career best at the tournament on her seventh appearance.

She next faces an unknown threat in Chan Yung-jan, who earned one of the biggest upsets of her career as the qualifier outlasted former world No. 1 Jelena Jankovic 6-7 (4/7), 7-6 (10/8), 7-5.

Second seed Dominika Cibulkova beat Poland's Ursula Radwanska 6-4, 6-4 while Russian fourth seed Nadia Petrova will line up against the Slovak after beating Varvara Lepchenko of the US 6-4, 2-6, 7-6 (7/5).

Taiwan's Chan, who is ranked 161, dealt a blow to the third seeded Janokovic's hopes as she won the second longest match of the season on the WTA Tour. The encounter lasted three hours, 13

minutes Ä four minutes less than the longest so far on the circuit.

Chan was playing in her ninth career quarter-final – her last was three years ago – and made the most of the opportunity against the Serb.

“It feels very special for me because she was a former No. 1,” said Chan. “This is my best result since (stomach) surgery at the end of last year (which cost her three months off court.)

“This really means a lot for me, since I was in quallies. It could be one of the best matches in my career.”

Jankovic, who has a home in the area, was up a set and led 3-1 in the second when she appeared to come unravelled after Chan took a medical timeout.

A broken string on the final point did not help her cause and provided a fitting punctuation to the disappointing end.

“I'm frustrated and disappointed,” said Jankovic. “I completely lost focus. It was so tough mentally and physically and my forehand let me down.

“I had the match under control and let it go. I let her come back, I messed up. When you're down you have to keep the focus.”

Chan will be in not so familiar territory when she plays only the fourth WTA level semi-final of her career. Her last came in 2008 in Strasbourg.

Jankovic has been on a slow road back to form over the past few seasons and had played in her first final last month in Birmingham since Cincinnati last summer.

Prior to this week, the Serb had lost in the first round 11 times this season. – Sapa-AFP