NEW YORK (AP) Petra Kvitova did not come to the U.S. Open planning to reach the quarterfinals or beat a top-five opponent to do so.
It's been less than nine months, after all, since the two-time Wimbledon winner's racket-holding hand needed surgery from a knife attack.
Here she is, though. Kvitova earned the biggest victory of her comeback Sunday night, eliminating No. 3 seed Garbine Muguruza, the reigning Wimbledon champion, by coming back in each set to win 7-6 (3), 6-3 in the fourth round at Flushing Meadows.
''I came here without any expectations,'' the 13th-seeded Kvitova said.
She is in the quarterfinals in New York for only the second time in 10 tournament appearances; the other such run came in 2015, when Kvitova lost at that stage to eventual champion Flavia Pennetta.
''I'm really enjoying it more than before,'' Kvitova said.
Now another showdown looms: Kvitova will play seven-time major champion Venus Williams on Tuesday with a semifinal berth at stake.
Williams, seeded No. 9, beat Carla Suarez Navarro 6-3, 3-6, 6-1 earlier Sunday.
Williams is, at 37, the oldest woman who entered the tournament. She is also the only one left who has won the U.S. Open, collecting titles in 2000 and 2001.
Asked whether those championships, long ago as they were, offer her any advantage against other players, Williams joked that if other players decide to just hand over matches, she'd gladly take it.
''I'm accepting all major credit cards,'' Williams said, ''and unforced errors.''
Kvitova still hasn't quite regained full strength in her left hand, the one operated on after being cut by an intruder at her home in the Czech Republic in December.
''Given all she's been gone through,'' Muguruza said, ''playing at this level is remarkable.''
Kvitova returned to the tour in late May at the French Open.
''I don't think that I can find the right words. It was a difficult time,'' Kvitova told the Arthur Ashe Stadium crowd after beating Muguruza. ''I didn't know how the journey would end.''
On Sunday, Muguruza jumped out to a 4-1 lead in the opening set and earned three break points for a chance to go up 5-1. But Kvitova managed to hold there, erasing that last break chance with a 94 mph ace out wide and starting a run in which she grabbed five of six games.
Muguruza again moved out front in the tiebreaker, at 3-2, before dropping five points in a row. At 4-3, Muguruza pushed a forehand volley long, then double-faulted to set point, before Kvitova put away an overhead to close it.
Muguruza broke to begin the second set, but Kvitova again turned things around quickly.
''Pretty good performance from her,'' said Muguruza, who still has a chance to move up to No. 1 in the WTA rankings for the first time after the tournament, depending on other players' results the rest of the way.
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