NEW YORK—Karolina Plisova, who has reached the second week of a Grand Slam for the first time, says she has not been experiencing her usual nerves.

The 24-year-old Czech had never previously been further than the third round of a major.

"The Grand Slams before, I wasn't feeling bad [at] any of them,” she said after defeating Anastasia Pavlyuchenkova  in the third round. “But, just, somehow the game on the court wasn't the way I wanted it to be. I was just a little bit tight. I wasn't playing my tennis.

"I [was] not playing my game. I cannot beat those players like this. I cannot be the one who is running. It was like this before in the Grand Slams.”

But capturing her first Premier title in Cincinnati two week ago appears to have given her more confidence on the big stage.

"I also knew I've been playing some good tennis [the] last few weeks," she said.

Pliskova, who will play Venus Williams in the fourth round, is No. 10 in the rankings.