Iga Swiatek came back from a set down to beat Qinwen Zheng 3-6 6-1 6-1 and reach the quarter-finals of the Western and Southern Open in Cincinnati.
The world number one will now turn her attention to Wimbledon champion Marketa Vondrousova.
Zheng, who defeated Venus Williams in the earlier round, threatened a major upset when she opened up a 3-0 lead against the Pole. The 20-year-old ended up taking the first set as Swiatek paid the price for 23 unforced errors.
Swiatek took a bathroom break between sets, during which she also changed her outfit. The French Open champion then forced two early breaks against the Chinese star and then again in the fifth game.
While Zheng did finally get a game on the scoreboard, it wasn't enough to stop Swiatek from closing out the set with yet another break.
The decider swiftly went the way of the Pole as she moved 3-0 up before serving out for what was – in the end – a comfortable victory.
"My coach had said to me, 'if you lose the set it might be a good idea to change your outfit, so you can kind of reset and go in the second set with a different vibe' – I tried this time and it worked," Swiatek said during her courtside interview, broadcast by Amazon Prime Video.
Vondrousova, the 10th seed, had earlier coasted past American Sloane Stephens 7-5 6-3 to reach the last eight and a showdown with the world number one.
Fourth seed Elena Rybakina, though, retired through injury during the second set of her third-round match against Italian qualifier Jasmine Paolini, who progressed with the score at 4-6 5-2.
Karolina Muchova also made it through to the quarter-finals with a hard-fought 6-3 2-6 6-3 victory over number eight seed Maria Sakkari.
