NEW YORK -- Coming into Monday’s fourth-round match, No.1-ranked Iga Swiatek had never lost to a player outside the Top 100 at a Grand Slam event. Before this year’s Wimbledon, Jule Niemeier had never won a major main-draw match.

That was the stark contrast Monday afternoon in Louis Armstrong Stadium, when Niemeier came tantalizingly close to springing the upset of this US Open. In the end, Swiatek escaped 2-6, 6-4, 6-0.

“Honestly at the beginning [of the second set] I felt like I’m just making a little bit less mistakes, but she also started playing less aggressively,” Swiatek told reporters. “It was easier for me to just play the ball in. Yeah, I think I started being more solid and I used a little bit more of the chances that I had.”

This is Swiatek’s third Grand Slam quarterfinal of the season. It was also her 19th 6-0 set win for Swiatek. It’s the most for any player since Serena Williams had 25 in 2013.

Swiatek will enter Wednesday’s match against No.8 Jessica Pegula feeling good about the matchup. Swiatek has won two of three, both in 2022 -- in the Miami semifinals, 6-2, 7-5 and the quarterfinals at Roland Garros 6-3, 6-2.

“I’m just proud that I didn’t lose hope,” Swiatek said. “I had a hard time pushing her back. I’m pretty glad it worked. I used my experience to keep my level the whole match.”

Match highlights: Swiatek hadn’t dropped a set through four matches, but Niemeier broke the two-time French Open champion in the opening game and raced to the first set.

Niemeier scored the first break of the second with a spectacular crosscourt forehand return followed by an uncharacteristic mistake from Swiatek. With an open court looming in front of her, she chopped a forehand volley into the net. Swiatek broke right back to make it 2-all.

The turning point came in the fifth game, when Swiatek erased a love-30 hole with four straight points, finishing with an ace, a forehand winner and another ace. The momentum continued when she broke Niemeier in the next game when the German sprayed a forehand long.

With a massive backhand winner, Niemeier returned the favor and brought the set back on serve, 3-4. Swiatek, clearly irritated with herself, proceeded to break Niemeier for the third straight time -- before Niemeier broke her back. Swiatek flashed a sarcastic thumbs up to her box after double-faulting it away.

A fourth straight break of Niemeier’s serve gave Swiatek the match-leveling second set. Early in the third, Swiatek broke for the fifth straight time and ran out to a lead she would not relinquish.

The hard-hitting 23-year-old German produced 14 unforced errors in the third set, compared to one for Swiatek. She also hit 13 double faults in the match. Swiatek, meanwhile, broke Niemeier’s serve seven of 13 times.

Niemeier making strides: Contesting only her third Grand Slam main-draw, Niemeier has been surprisingly good in big matches. In her only previous meeting with a Top 10 player, she upset No.2 Anett Kontaveit in the second round at Wimbledon. It’s difficult to believe that coming into the US Open she had never won a Tour-level hard-court match.

Harder still to imagine that her last tournament before this was the ITF $60,000 in the Bronx. Niemeier lost to qualifier Lesley Pattinama Kerkhove, ranked No.199, in the first round and received $557 in prize money. Niemeier's reward for reaching the fourth round is $278,000.