French qualifier Severine Bremond earned a place in the quarter-finals with a remarkable 7-6 (13-11) 6-3 win over 18th seed Ai Sugiyama.
Sugiyama had three set points when she led 5-4 in the first set but Bremond then won six points in a row and eventually earned a tie-break.
Sugiyama led that 4-0 and had nine set points throughout the 70-minute set but Bremond took it at the third attempt.
Bremond then hit back from 2-0 down in the second set to seal a famous win.
Na Li became the first Chinese player to reach the quarter-finals of a Grand Slam as she edged out 10th seed Nicole Vaidisova 4-6 6-1 6-3.
Vaidisova took early control of the match by taking the first set but Li was unfazed and hit back to rush through the second and earn a decider.
The third set was the longest of the match at 41 minutes and Li held her nerve to earn the victory.
She will play second seed Kim Clijsters in the next round.
Li said she was delighted to have become the first player from her country to reach the last eight of a Grand Slam event.
"I'm very proud of myself for what I have achieved and I am very proud for my country," said Li.
"Chinese women tennis players are getting better and better."
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