The unseeded American knocks out 2010 champion and will play Kvitova in French Open's round of 16.
Lepchenko stuns Schiavone to find herself in unfamiliar territory
Varvara Lepchenko's tennis odyssey carried her from the ex-Soviet nation of Uzbekistan to an apartment in Pennsylvania and US citizenship last year.
On Saturday, she arrived somewhere she has never been before - the fourth round of a grand slam tournament, thanks to a surprising 3-6, 6-3, 8-6 victory at the French Open over 2010 champion Francesca Schiavone of Italy.
Unseeded and ranked only 63rd, Lepchenko gutted out a three-hour, two-minute win over the 12th-seeded Schiavone, who also was last year's runner-up at Roland Garros.
Lepchenko joined 19-year-old Sloane Stephens, who won on Friday, to give the United States two unseeded women in the round of 16 at a major tournament for the first time since Wimbledon in 2002.
"Unexpected," said the 26-year-old Lepchenko, never before past a second round of a grand slam, let alone third. "I mean, I didn't even expect it. I mean, I just worked hard and tried to believe in myself. I'm a fighter ... in real life and on the tennis court."
She was born in Uzbekistan's capital, Tashkent, then moved with her father and sister to Florida more than a decade ago, granted political asylum so she could leave the Central Asian country to the north of Afghanistan that the US government has pressed to improve its human rights record.
"There was no future for me, no future for my career," Lepchenko said of her birthplace.
"I wouldn't be able to make it as far as I am right now if I was back in Uzbekistan."
The victory means Lepchenko is certain to qualify for the US team at the London Olympics, leaving Venus Williams vulnerable because Stephens, who is ranked lower at the moment, is still in the tournament.
Wimbledon champion Petra Kvitova is next up for Lepchenko after she eventually got past Nina Bratchikova 6-2, 4-6, 6-1.
Defending champion Li was also involved in a three-setter but the Chinese player survived her first test, seeing off 20-year-old American Christina McHale 3-6, 6-2, 6-1.
Li, who now faces Yaroslava Shvedova, said: "In the first set I think I always followed what she did. I was feeling like she's the champion on the court. But I was happy I changed a bit at the beginning of the second set to play my way.
"She's a very dangerous player. I was happy I could win the match today because I have more experience."
Klara Zakopalova beat 22nd seed Anastasia Pavlyuchenkova 6-3, 7-5.
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