Injury that 'sucks' helps propel Pegula into US Open semi-final
Sixth-ranked Pegula triumphed over the 2022 champion and four-time French Open winner 6-2, 6-4.
Victory ended Pegula's run of losing all six Grand Slam quarter-finals in which she had played and extended her streak to 14 wins in 15 matches on US hard courts this summer.
However, she believes the foundation of her charge into the New York semi-finals was laid by the effects of a rib injury which forced her to sit out the European clay court swing, including the French Open.
She had already been sick earlier in the season following a dispiriting early exit from the Australian Open when she was "burnt out" with an "immune system that was kind of shot".
"By the time I got injured, I think I was ready to go. I think once I kind of reset and kind of got back to normal, getting injured then kind of just made me more hungry," said Pegula.
"I was like, okay, this sucks, like, I want to be playing, like I'm ready. To be kind of set back like that I think helped me come back."
She marked her return to action by winning the grass-court title in Berlin.
"In Berlin I was super fresh and wanting to win these matches, and kind of fired up," said Pegula.
Despite second-round losses at Wimbledon and the Paris Olympics, Pegula has been virtually unstoppable since winning the Toronto title and finishing runner-up in Cincinnati.
"Finally I can say I'm a semi-finalist. I lost so many of these damn things," said Pegula after her fourth career win against Swiatek.
Pegula raced into a double break in the first set as Swiatek was plagued by mistakes.
By the end of the opener Swiatek had hit just three winners and committed 19 unforced errors as her game fell apart under the Arthur Ashe Stadium lights.
It was a dramatic slump for the top seed, who hadn't faced a single break point in her three preceding matches.
Pegula turned the screw for a 2-1 lead in the second before Swiatek retrieved the break.
But the Polish star couldn't capitalise and was broken again when a forehand error handed Pegula a 4-3 edge.
The American claimed victory on a third match point when Swiatek went wide again for her 41st and final unforced error of the night.
As Pegula looks ahead to a Thursday semi-final against Karolina Muchova, Swiatek was left to ponder a rollercoaster season at the Grand Slams.
There was the high of a fourth French Open but that was sandwiched by third round exits at the Australian Open and Wimbledon.
At the Paris Olympics, played on her favourite Roland Garros courts, she had to settle for the bronze medal.
"I'm always trying to have lower expectations. I feel like when I have high expectations, I never perform well," she said.
"But it's hard to have low expectations when everybody is expecting something from you."