Top-seeded Naomi Osaka pulled out of her Melbourne Summer Set 1 semifinal against Veronika Kudermetova on Saturday, citing the intensity of recent matches as the cause for her withdrawal.
"Sad to withdraw due to injury from my match today, my body got a shock from playing back to back intense matches after the break I took," Osaka said on Twitter.
"I'll try to rest up and I'll see you soon!"
Four-time Grand Slam champion Osaka beat German Andrea Petkovic 6-1, 7-5 in the quarterfinal on Friday, less than two weeks out from the start of the Australian Open.
The Japanese former world No. 1 has struggled for form since withdrawing from the French Open in May following a row with tournament officials over required media appearances, which she said had a negative impact on her.
Osaka also pulled out of a warm-up event in the build-up to last year's Australian Open with "a niggling injury."
The Australian Open begins on Jan. 17.