INDIAN WELLS, CA, USA - No.5 seed Karolina Pliskova ended the breakout week of 16-year-old American wildcard Amanda Anisimova with a 6-1, 7-6(2) win in the fourth round of the BNP Paribas Open. 

After a one-sided affair in the first set where the former World No.1 took advantage of an unsettled start by her teenaged foe, Pliskova was forced to dig deep to win the match in straight sets, as she twice served to stay in it.

"I think I started pretty well today. I was playing aggressive and she didn't have time to play her game," Pliskova said on-court after the match.

"I backed up a little bit in the second set, and she started to play well, hitting some lines and some deep balls, which was trouble for me. I'm just happy that I held my serve to the tiebreak, and in the tiebreak I was a little bit better."

Pliskova won the first seven points of the match on her way to breaking serve twice in the opening set, taking advantage of 13 unforced errors from the American teenager as each player struck five winners.

Anisimova mounted a stern challenge in the opening games of the second set, holding serve to begin to take her first lead and keeping the pressure on in Pliskova's service games.

Though she fell behind a break in the fifth game of set two, the wildcard - who upset Pliskova's compatriot Petra Kvitova in the previous round to put an end to the Czech's 14-match winning streak - answered back right away and kept the set on serve through to a tiebreak.

Once there, however, Pliskova raised her level from a mini-break down at 2-1, and won the last six points to clock in victory in one hour, 33 minutes. 

Overall, the Czech responded incredibly well to a stunning improvement from Anisimova, who struck 23 of her 28 winners for the match in the second set and just 16 unforced errors.

"I think my game, match from match, is improving here. I feel much better than in the first and also second round or second match, so just happy it's going a little bit more up," Pliskova assessed. "I played tough matches here, some tiebreaks, one three-setter yesterday. It always gives you some confidence when you go through those tough moments."

Pliskova saved five of the six break points she faced in set two, and won 71 percent of points behind her first serve in the match.

Following the victory, the Czech was more than complimentary of the reigning junior US Open champion.

"Obviously she's 16, so she's not scared. You can see she's hitting the ball without thinking, but everybody is playing like this when they are 16. I think this will change a little bit in the future, but for sure the game is good and not really any weakness," Pliskova said.

"I think everything pretty solid. She can for sure play well...I was ready. I didn't want to think that it's gonna be easy because she's 16. She had that confidence after those matches what she was playing here. She was playing the tournament here, and she won juniors."

A five-time quarterfinalist at WTA Premier Mandatory events, Pliskova advances to the last eight in Palm Springs for the third time in her career, having reached the semifinals in each of the past two years. 

"For sure, I like this tournament so much and I've been playing pretty well every year here," she added after the match. "It just makes me extra confident to come into this tournament, that I know I can win a few matches here every year. It's just great that even this year, I'm back in the quarterfinals. I'm going to be ready for it and I want to enjoy."

Pliskova's victory sets up a quarterfinal encounter for the World No.5 against the winner of the match between Naomi Osaka and Maria Sakkari.