Keothavong, the world number 87, won 6-2 3-6 6-4 and the 24-year-old from Hackney could now face fifth seed and Olympic women's singles champion Elena Dementieva of Russia, who was on court against France's Pauline Parmentier.

Playing in her first grand slam outside of Wimbledon, where her best result came this year as she reached the second round, Keothavong had reached the second round with a defeat of American qualifier Alexa Glatch.

She got off to the best possible start against Schiavone by breaking her opponent's serve in the opening game, then holding her own first service game to gain a grip on the first set at 2-0.

While Schiavone appeared out of sorts, Keothavong was the picture of confidence, winning the fourth game with an ace to go 3-1 up and breaking again in the seventh game to move to 5-2 and serve out for the set.

That game proved to be a battle with Keothavong earning three set points and surviving three break points before taking the first set.

Schiavone rallied in the second set, with Keothavong failing to recover from the Italian's first break of serve in the second game and going onto to lose it 6-3.

That teed up a tense deciding set which went with service until the fifth game, Schiavone making the crucial breakthrough and then holding her serve to move 4-2 up.

The pendulum quickly swung the other way though as Keothavong won the next three games to leave Schiavone serving to save the match.

She proved unable to do so, the Italian losing the match on a double fault to leave the Londoner celebrating a famous victory.