Czech teenager Nicole Vaidisova overcame a slow start to tame top seed and world number one Amelie Mauresmo 1-6, 7-5, 7-6 in the Kremlin Cup quarter-finals in Moscow on Friday.
The eighth-seeded Vaidisova recovered from a horrendous first set to take a 4-2 lead in the decider, but the powerful Frenchwoman reeled off three consecutive games to go 5-4 up.
The 17-year-old Czech would not be denied, however, as she prevailed over Wimbledon champion Mauresmo after a two and half hour battle, saving three match points in the process.
Vaidisova will now take on fifth-seeded Russian Nadia Petrova, who beat compatriot Vera Zvonareva 7-5, 6-1 in the first match on centre court.
Mauresmo joined US Open champion and second seed Maria Sharapova on the sidelines after the Russian was forced to pull out of her quarter-final with a foot injury.
The 19-year-old had complained of a pain in her right foot after her second round victory on Wednesday.
"I will not be able to step out on the court today. If I'm not able to give 100 percent, I'd rather not play at all," she was quoted as saying on the tournament website.
Fellow Russian Anna Chakvetadze benefited from Sharapova's injury, moving into the semi-finals without hitting a ball. She will face either fourth-seeded Russian Elena Dementieva or sixth seed Patty Schnyder from Switzerland, who are playing later on Friday.
Men's top seed Nikolay Davydenko, chasing a place in the season-ending Masters Cup in Shanghai next month, beat Max Mirnyi of Belarus 6-3, 7-5 to move into the semi-finals.
The Russian stands fifth in the ATP Champions Race and victory in Moscow would go a long way to securing a place in the eight-man finale.
Davydenko will now meet veteran Frenchman Fabrice Santoro after the 33-year-old seventh seed booked his place in the last four with a 6-3, 7-5 defeat of Germany's Philipp Kohlschreiber.
Former world number one and home favourite Marat Safin is in quarter-final action later against Serbian Janko Tipsarevic while Russian Igor Kunitsyn plays France's Arnaud Clement.
