Unseeded Varvara Lepchenko of the United States beat 2010 French Open champion Francesca Schiavone of Italy 3-6, 6-3, 8-6 in the third round at Roland Garros on Saturday.
The 63rd-ranked Lepchenko never had made it beyond the second round at any Grand Slam tournament.
But she came back to eliminate Schiavone, who was the runner-up at last year's French Open.
Lepchenko joins Sloane Stephens, who won Friday, to give the U.S. two unseeded women in the fourth round at a major tournament for the first time since Wimbledon in 2002.
Lepchenko was born in Uzbekistan and now lives in Pennsylvania. She became a U.S. citizen last year.