Madrid - Unheralded Aravane Rezai thrust herself into contention as a Roland Garros threat on Sunday with a stunning 6-2 7-5 victory over Venus Williams to win the Madrid Masters after a week-long, giant-killing run.
The upset in just under one and three-quarter hours marked the biggest success in the career of the 23-year-old Frenchwoman, whose previous two WTA titles were in Strasbourg and Bali.
Sunday's victory was Rezai's third major triumph this week after knocking out former number one players Justine Henin in the first round and Jelena Jankovic in the quarters.
Williams, who was chasing a 44th career crown, was run down in the 27-minute opening set and was unable to take advantage of a 4-1 lead in the second.
Instead of folding and saving strength for a deciding third set, Rezai, who hits every ball with brute force, managed to claw her way back, saved a Williams set point in the eighth game and five more a game later to hold for 5-all.
A break of the frustrated American gave Rezai a 6-5 lead, with the number 24 calmly serving out the biggest victory of her career a game later.
"I just cannot believe this, said the stunned winner.
"She played very well and I've always respected her as a player and a champion. I just tried my best today and it worked well for me."
Williams, winner of nine clay titles, limited herself to one sentence during the painful trophy ceremony: "She played well, congratulations," said the American who despite the setback will return to the world number two ranking on Monday behind sister Serena.
Rezai now stands 9-4 on clay this season and will have it all to prove with the French Open getting underway on Sunday and where she will be added to the list of dangerous outsiders.
The 23-year-old of Iranian heritage has had limited success on clay until this week, going only into the second round at Marbella, losing in the first round at Barcelona, and going 1-1 in Fed Cup against Germany on the surface.
She then lost in the Rome second round last week.
Rezai made the most of her chances, refusing to roll over in what looked to be the start of a Williams fightback midway through the second set.
The Frenchwoman converted on five of ten break points while Williams managed to break just twice on 13 opportunities.
Williams came in with title at her last three clay finals - Acapulco in 2009 and 2010 and Istanbul five years ago.
The veteran was playing in her 70th WTA final and stands 43-27.
Rezai will move into the top 20 as a result of her efforts and stands 2-1 over Williams after beating the American in Istanbul in 2007 while losing that year at Amelia Island, both times on clay.