NEW YORK -- Iga Swiatek is still only 21 years old, but she’s displayed some frightening consistency this year. During a 37-match winning streak, she won her second major at Roland Garros and WTA 1000s in Doha, Indian Wells, Miami and Rome.

She’s trying to become the first player since Serena to win seven titles in a single year -- and that was eight years ago, when Williams also became the last No.1 seed to take this title.

Swiatek took another step Saturday at the US Open. She defeated American Lauren Davis 6-3, 6-4 in a third-round match. But it was tougher than the score line indicated.  

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“I could not find my rhythm today,” Swiatek said in her on-court interview. “She played pretty smart. I’m pretty happy at the end that I could put balls in. 

“I’m just trying to enjoy any match, even when I’m not perfect.”

In the summer hard-court season, though, Swiatek’s won only four of seven matches. 

Against Davis, she came out firing, hitting nine winners (two aces) in the first two games, the second one a break of Davis’ serve. That offense, combined with her usual spotless defense, marked by her trademark squat shots and some screeching slides, was a lot for Davis to take in. Before serving at 2-5, Davis called for the trainer, who checked her temperature and blood pressure.

Swiatek won the first set when a 108 mph offering was not returned.

Davis came back in the second, taking the first three games. Swiatek got her first game after a grueling five-deuce affair that left both players winded. Davis saved three break points in the next game and eventually held.

Swiatek broke back to get to 3-4 and back on serve. Davis wound up losing the last five games of the match. Swiatek converted only three of 14 break points.

This equals Swiatek’s best result at the US Open, her 2021 run. She remains undefeated against players ranked outside the Top 100 in Grand Slam play (15-0). She’s won 53 matches this season and is already closing in on the most recent standard, 57, set three years ago by Ashleigh Barty.

Davis, in her 10th US Open main draw, equaled her best effort in a major by reaching the third round. The last (and only other) time she faced a World No.1, she played a heroic match, losing to Simona Halep 15-13 in the third set at the 2018 Australian Open. Davis is now 11-15 for the year.

Swiatek rose to the No.1 ranking back in April after Barty announced her retirement. The past five months have given her a greater appreciation of Serena’s staying power over the years.

“Being in this situation,” she said, “I know how tough it is sometimes to find balance and to actually stay focused on the proper things. I think she did very well. I have huge appreciation because it’s one of my goals actually to be consistent throughout my whole career, staying Top 10 for a long, long time.

“She was No.1 for a long, long time, so it’s pretty crazy. For sure, I understand it little bit more right now, how much work she has put into it.”

Swiatek will face Germany's Jule Niemeier in the fourth round. A quarterfinalist at Wimbledon earlier in the summer, Niemeier stunned Zheng Qinwen 6-4, 7-6(5) to make the Round of 16 in her tournament debut. Ranked No.108, Niemeier outhit Zheng with 22 winners, nearly doubling up on the rising Chinese star's 12.