Top-seeded Naomi Osaka has withdrawn from her Melbourne Summer Set 1 WTA event semi-final against Veronika Kudermetova on Saturday, citing the intensity of recent games as a cause for her withdrawal.

“I had a lot of fun playing here in Melbourne. Unfortunately, I have an abdominal injury which I need to rest and prepare for the Australian Open,” Osaka said in a statement issued by Tennis Australia.

“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 added later on Twitter. “I’ll try to rest up and I’ll see you soon!”

The Australian Open begins on Jan. 17.

Kudermetova on Sunday will face second-seeded Simona Halep, who beat Zheng Qinwen 6-3, 6-2 in the other semifinal in the Summer Set 1 event.

Four-times Grand Slam champion Osaka beat German Andrea Petkovic 6-1 7-5 in the quarter-final on Friday, less than two weeks out from the start of the Australian Open.

The Japanese former world number one 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”.