Petra Kvitova was pleased with her recovery from a slow start as she revelled in her fourth-round victory over Garbine Muguruza at the US Open.

The Czech star reached the quarter-finals in New York for the second time in three years after a 7-6 (7-3) 6-3 win over third seed Muguruza on Sunday.

Kvitova triumphed despite falling 4-1 behind in the first set and then failing to serve it out in the 12th game.

But the two-time Wimbledon champion was satisfied with her performance, saying: "I feel great, of course.

"I was happy that I managed to win the match. Over the last couple of points, I got a little bit tight. You can just dream about it, but when you there, it's just different. It's about experience again.

"It was a great fight. I struggled a little bit from the beginning. I was rushing from the beginning, so I just need to really try to be a little bit more calm, play some rallies.

"It wasn't really nice when I couldn't serve out the set. That was a really big game from my side at 6-5. I didn't start well in the tie-break as well. I was glad I was just trying to stay in the rallies.

"I won the first [set], which I think was kind of the key of the match afterwards."

It was Kvitova's third consecutive victory over Muguruza, who managed just seven winners to the Czech's 24.

The two-time major winner paid tribute to Kvitova, saying the 27-year-old – who faces Venus Williams in the last eight – was simply too good.

"I think she was serving very good. In the key moments, she finds big serves. It is complicated when she hits lots of aces, or just strong serves," Muguruza said.

"She was playing good, a lot of winners. She was playing very good with the forehand today, moving well, as well. Pretty good performance from her."