Spain's world number three Garbine Muguruza battled a muscle problem to overcome Kiki Bertens and reach the quarter-finals of the Sydney International on Wednesday.
A week after retiring from the Brisbane International with cramps, leading Australian Open contender Muguruza was ahead 2-1 in the opening set when she sought a medical time-out.
"Since the start I felt a little bit my adductor (muscle), and I already felt it in Brisbane, so I thought I was going to be much better but in fact it came back," Muguruza told reporters.
"I asked for a medical timeout to try and make it better. It worked."
Muguruza showed few ill-effects upon her return to the court, claiming six of the next eight games to take a commanding lead against the 32nd-ranked Dutchwoman.
The Spanish top seed Bertens claimed the first set before needing a tiebreaker to see off her opponent 6-3, 7-6 (8/6).
The reigning Wimbledon champion will face the winner of the all-Australian second-round match between Daria Gavrilova and Samantha Stosur for a spot in the final four.
"It's always difficult when you have the pain and you have to play," Muguruza said.
"I never really get to play a tournament right before a Grand Slam, but I wanted to come to Sydney and play. I adapt a little bit my game to the circumstances, and I'm happy that I won.
"It was close. But I'm happy to play a match and to win, of course. That was the point to come to Sydney."
Poland's Agnieszka Radwanksa advanced to her fifth Sydney quarter-final with a straight-sets win over American qualifier Catherine Bellis 7-6 (7/4), 6-0.
Radwanska will play Italian qualifier Camila Giorgi, who eliminated two-time Wimbledon champion Petra Kvitova 7-6 (9/7), 6-2.
In the men's event, Spanish top seed Albert Ramos-Vinolas was knocked out by Italy's Paolo Lorenzi 6-3, 7-5.
The Spanish world No.22 needed treatment for a leg problem early in the second set but continued playing, without success, as Lorenzi moved into the quarter-finals.
Lorenzi will play Russian qualifier Daniil Medvedev for a semi-final berth.
French pair Adrian Mannarino and Benoit Paire progressed to the last eight with victories on Wednesday.
Fifth seed Mannarino downed Lithuania's Ricardas Berankis 6-2, 6-1, while Paire needed three sets to get past Argentina's Leonardo Mayer 6-2, 3-6, 6-1