AFP - Russian seventh seed Svetlana Kuznetsova survived a fightback from America's Serena Williams to book a French Open semi-final date with Australian 30th seed Samantha Stosur here on Wednesday.

Kuznetsova led by a set and 4-1 against world number two Williams, the 2002 champion, before the American fought back to force a deciding set, with the Russian world number seven eventually prevailing 7-6 (7/3), 5-7, 7-5.

Stosur eased through her quarter-final against unseeded Romanian Sorana Cirstea, winning 6-1, 6-3 to become the first Australian woman in the last four since Nicole Provis in 1988.

"I'm over the moon. Happy, excited, every single positive emotion possible at the moment," said Stosur, who spent nearly 12 months out of the game after being laid low by fatigue-inducing Lyme's disease in 2007.

"Over the last couple of years it's been pretty tough at times. The French Open last year was my first Grand Slam after being out for nearly a year and from last year to this year, I just can't compare it."

World number seven Kuznetsova, a runner-up here in 2006, broke twice to open up a 3-0 first-set lead against Williams, the double-break secured with a superb curving backhand winner down the line, before conceding a break with a double-fault in her next service game.

Williams broke again when Kuznetsova was serving for the set at 5-4, but after surviving a set point at 5-6 down on her own serve the Russian played superbly to prevail in the subsequent tie-break.

The American found herself 4-1 down after an early break in the second set and Kuznetsova served for the match at 5-3 up after exchanging breaks with her opponent, only for Williams to dig deep for a double-break before levelling the match with an ace.

Williams saw off two match points at 4-5 down in a tense decider before finally capitulating with a tired backhand to hand Kuznetsova only her second victory over the 10-time major-winner in seven attempts after 2hr 46min on court.

Stosur, who is bidding to become the first Australian winner at Roland Garros since Margaret Smith-Court in 1973, was rarely troubled in a one-sided encounter against world number 41 Cirstea.

The 19-year-old Romanian had beaten three seeds, including Serbian world number five Jelena Jankovic, en route to the last eight but a nervous double-fault saw her broken in her first service game.

The big-serving Stosur, ranked 32 in the world, then broke again when Cirstea scooped a crosscourt forehand wide before serving out for the set in 27 minutes.

A more tenacious Cirstea forced Stosur to save four break points in the opening game of the second set, before the Australian broke for a 2-1 lead.

Stosur's advantage stretched to 4-1 when Cirstea sliced a backhand into the tramlines in her next service game, with Stosur surviving a late rally from her opponent before breaking again to close out the match.