In the WTA draw, world No 1 Iga Swiatek changed her dress after losing the opening set and came back a new woman, defeating China's Zheng Qinwen 3-6, 6-1, 6-1.
"My coach told me a few weeks ago it might be a good idea to change clothes and reset," the Pole said. "I tried it and it worked, I got a different vibe in the second set – thank you, coach."
Wimbledon champion Marketa Vondrousova beat Sloane Stephens 7-5, 6-3 to reach the quarterfinals of an event in which she was 0-3 in prior appearances.
"It has been really special this week. I came here not knowing how I would play," she said. "It's such a pleasure to be back as Wimbledon champion."
Third-seeded Jessica Pegula, last week's Montreal winner, was defeated in a match which concluded in light drizzle, losing 6-4, 6-0 to Marie Bouzkova.
Fourth seed Elena Rybakina joined No 8 Maria Sakkari in exiting.
Rybakina, last year's Wimbledon champion, retired at 6-4, 2-5 against Italian qualifier Jasmine Paulini while Sakkari went down 6-3, 2-6, 6-3 to Czech Karolina Muchova. Croatia's Donna Vekic retired with viral illness, handing a 5-2 decision to three-time Grand Slam finalist Ons Jabeur.
Seventh seed Coco Gauff won a battle of teenagers over Czech Linda Noskova 6-4, 6-0 in 62 minutes.