Naomi Osaka booked her place in the last eight with a straight sets win over Julia Grabher in the ASB Classic in Auckland.
The four-time Grand Slam winner, who had her 2024 season curtailed by a back injury, did not drop her serve against the Austrian.
Osaka had to endure a lengthy rain delay after taking a tight opening set 7-5.
She broke Grabher's serve in the sixth game after the resumption and served out to win 6-3.
It is the Japanese star's first quarter-final appearance in six months, and she said on wtatennis.com: "I'm not a really confrontational person. But, when you're on the court, it's like you're in a boxing match.
"You need to have the will to fight more than the other person and I feel like I finally found that again. I think I'm ready for the battle."
Former Australian Open champion Sofia Kenin went out as she lost 4-6 7-6 (7) 7-6 (3) to Clara Tauson in a marathon clash.
After going down in the first set 6-4, Tauson staged a comeback in the second and grabbed the victory after a tight third set.
Seeds continued to fall at the Brisbane International and there was a career-best victory for Australian wild card Kimberly Birrell, who defeated second seed Emma Navarro 7-5 7-5.
Marta Kostyuk, Magdalena Frech, Liudmila Samsonova and Dayana Yastremska are also out but third seed Daria Kasatkina, 10th seed Victoria Azarenka and 12th seed Linda Noskova did make it through to the third round.