Petra Kvitova summoned her A-game at Flushing Meadows on Sunday night to knock Wimbledon champion and the pre-tournament favourite for the US Open title Garbiñe Muguruza out in straight sets to reach the quarter-finals of the last Grand Slam of the year.
Kvitova, a double Wimbledon champion, suffered a career-threatening injury to her left playing hand, when an intruder stabbed her at her home in December but she has been recovering faster than expected.
Seeded 13th at Flushing Meadows, Kvitova went through the early rounds without dropping a set but Sunday's challenge on Arthur Ashe Stadium was supposed to be trickier as she was facing the in-form Spaniard.
She fell 4-1 behind at the start but then won 12 of the 17 remaining games to prevail 7-6, 6-3.
Kvitova: "I didn't have any expectation to play well here"
"I should change my perspective about it. Maybe that's why I didn't ever have any expectation to play well here. That's why probably I am playing more relaxed and more free maybe," she told a news conference.
"I'm always putting a little bit of pressure on myself at Wimbledon because of the titles, I do have them. But I'm trying to find a rhythm at the US Open. I'm not going on-site the day off. I'm staying by Central Park which is pretty relaxed."
Next up for Kvitova is local favourite Venus Williams, the ninth seed who this season reached her first two grand slam finals since 2009 at the Australian Open and Wimbledon.
But Kvitova is relishing the challenge.
"I think that she's playing amazing on the majors this year. I mean, she is really playing very, very well on the big stages," said Kvitova. "She played the final of Wimbledon. She's a champion. It's what we all know.
"It will be a great match for me to step on Ashe again probably and play there. I mean, we always had tough battles.
"I will try my best. I mean, she has a big serve, big server of course. She has something special which the other players don’t have. That's what I will try to play again probably, similar game as today."
Sevastova ousts Sharapova
Maria Sharapova's Grand Slam return after a 15-month doping ban was also derailed on Sunday in the fourth round but the former world number one considered it a major step in her comeback.
Latvian 16th seed Anastasija Sevastova rallied to eliminate the five-time Grand Slam champion 5-7, 6-4, 6-2 on Arthur Ashe, booking a quarter-final against American Sloane Stephens, who ousted Germany's Julia Goerges 6-3, 3-6, 6-1.
Sharapova, the 2006 US Open winner, was able to find the positives after making 51 unforced errors to only 14 by Sevastova, whose 21 winners were half the 30-year-old Russian's total.
"Reflecting back on the week, I can be happy," Sharapova said. "It has been a really great ride. Ultimately, I can take a lot from this week."