NEW YORK, NY, USA -- No.6 seed Petra Kvitova of the Czech Republic powered her way into the fourth round at the US Open on Friday, fending off a challenge from surging American Jessica Pegula before obtaining a 6-4, 6-3 victory.

"I think the whole match was at a pretty good level," Kvitova told the media, after her win. "We both played nice tennis, I would say."

It becomes a milestone 20th fourth-round appearance at a Grand Slam event for World No.12 Kvitova, whose best finishes at the US Open are quarterfinal results in 2015 and 2017.

In the first meeting between the two players, two-time Wimbledon champion Kvitova was made to work in many of her service games by World No.63 Pegula, who is coming off of a quarterfinal appearance at the Western & Southern Open just last week. Nevertheless, Kvitova was able to close out the straight-set victory after 84 minutes of play.

"In the second set, I was down, I came back, It was a really big fight," said Kvitova. "There were two or three games where I really had to fight very hard, and that probably was the turning point. I felt better, I was even, I was holding my serve. I tried to go really more for the volleys because she plays really great from the baseline."

The Czech was more efficient on second-service points than her opponent was, as Kvitova won just over half of those points, as opposed to 35 percent by Pegula. Kvitova also won 15 of 18 points (83 percent) when she charged to the net during the encounter.

"I had to push her, push her, push her, then wait for my chances to get the winner or go to the net or something like this," the Czech continued. "Definitely my serve was helping me today in the important points, so I’m happy with that."

Kvitova will face another hard-hitting American in the round of 16, when she meets Shelby Rogers, who ousted Madison Brengle earlier on Friday. Rogers shocked Kvitova 6-0, 6-7(3), 6-0 in their only previous meeting, which came at the 2016 French Open en route to the American’s career-best quarterfinal showing at a major.

"I know Shelby played great in Lexington, she’s had a great run here so far as well," said Kvitova. "I know she’s had some injuries, so it’s great to see her back playing great."

"Big serve, big hitter," Kvitova added, looking forward to her match against Rogers. "I think it will be about the first two shots in the rally. We will see, I will [have] to be prepared for everything."

Kvitova reeled off the first ten points on her serve in the match, but after that streak ended, she found herself in danger at 2-2 when she slid from 30-0 to 30-40. Good serving and depth of shot helped the Czech fend off two break points as she stayed in front of Pegula, holding for 3-2.

Pegula was cruising through her service games in the first half of the opening set, but the American hit a roadblock at 4-3, when a searing forehand winner gave Kvitova her first break point of the match. The Czech then converted that chance with an error-forcing service return to move ahead 5-3 and serve for a one-set lead.

Kvitova squandered that opportunity, hitting a double fault down break point to let Pegula back on serve at 5-4. However, the American misfired on a series of forehands in the subsequent game to give Kvitova two set points, and Pegula double faulted on the first to cede the opening frame to the sixth seed.

Pegula started the second set off strongly, as she broke Kvitova for the second time via deep returns. But the Czech rebounded and reached parity again at 2-2, as she edged closer to a straight-set victory over a dangerous opponent.

The American, though, nearly reclaimed the lead in the frame, chasing down a dropshot and firing it back with a winning forehand to reach double break point for a 3-2 advantage. Kvitova, however, found thundering groundstrokes in the corners when she needed them most, extricating herself from a tricky situation to hold on for 3-2.

Kvitova then put down the hammer when she converted her fourth break point of a long game to move ahead 5-3 and serve for the match. The Czech required just a single match point to polish off the victory and edge into the US Open fourth round for the sixth time in her storied career.

2020 US Open highlights: Kvitova powers past Pegula