Iga Swiatek won two tiebreaks in a single match for the first time in her career Saturday, outlasting No. 25 seed Marie Bouzkova 7-6 (3), 7-6 (3) in 2 hours and 27 minutes to reach the US Open fourth round for the sixth straight year.

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“It got pretty physical. [There were] many long rallies, and sometimes I had to attack many times because Marie was defending really well and getting every ball back — also using her opportunities when she had a chance,” Swiatek said in her on-court interview. “I just wanted to be solid and play one more ball in and not aim too much. It was really tricky.”

Despite being pushed throughout and having to save three set points in the second set, Swiatek remains undefeated against Bouzkova at the WTA Tour Driven by Mercedes-Benz level. She leads the head-to-head 4-0 and hasn’t dropped a set. She has now won 13 of her last 14 matches overall, losing only to Jessica Pegula in the Cincinnati semifinals.

It was an unusual victory for Swiatek beyond the first-time scoreline. Her serve wavered — she won just 60% of her first-serve points and was broken five times — but the rest of her game held firm. She excelled at the net, winning 15 of 17 points, and finished with 35 winners, 15 more than Bouzkova. She also punished the Czech’s second serve, winning 64% of those points to secure five breaks of her own.

The match itself was a break-fest. Swiatek was the first to hold for 3-2 in the opening set before Bouzkova answered for 3-all. After breaking for 6-5, Bouzkova served for the set, but broke again to force the tiebreak. Bouzkova double-faulted to hand Swiatek a mini-break at 2-0, and the Pole closed it out from there.

Bouzkova nearly forced a decider, leading 6-5 as Swiatek served to reach another tiebreak. The Czech held three set points, the last saved by a Swiatek volley winner. It proved her final opening, as Swiatek grabbed the mini-break on the first point of the breaker and never looked back.

“I tried not to think of these points as set points. I tried to play them as I would any other point. I didn’t want to create too much pressure,” Swiatek said in her post-match press conference. “Obviously if I’m focused well, I don’t know what the score is. So that’s the time in the match where I can just focus on my tasks, and then I can be more consistent no matter what the score is.

“It wasn’t easy to do that today, but that’s how I felt in the tiebreaks, as well.”

Swiatek is now 7-2 in tiebreaks in her US Open career.

The win sets up a box-office fourth-round matchup with Zheng Qinwen, who saved a match point and rallied from 5-0 down to defeat No. 22 seed Madison Keys earlier Saturday. Swiatek has won seven of their eight meetings, losing only at the 2024 Olympics in Paris.

And for what it’s worth: Swiatek is undefeated against qualifiers and lucky losers at Grand Slams (15-0).