Naomi Osaka said the scheduling of lead-up events was a factor in her decision to withdraw from the Gippsland Trophy on Saturday.
The three-time major champion opted to pull out of her scheduled semi-final against Elise Mertens due to a shoulder injury.
Osaka, 23, was due to play a fourth match in five days, but decided to withdraw ahead of the Australian Open starting on Monday.
"Anyone that's kind of followed me for a bit knows that I've kind of had a slight shoulder thing since like 2018 in Beijing," the Japanese star told a news conference.
"It kind of flared up again because I played a lot of matches back-to-back. But, for me, my main focus is hoping I can rest enough before the Open."
Osaka, who will face Anastasia Pavlyuchenkova in the Australian Open first round, said the time between the Gippsland Trophy and year's first major also impacted her decision.
"I would say it is a factor because for me, I don't normally play the tournament right before a slam," she said.
"But I felt like it was really necessary to get matches in. I think everyone felt that way.
"I'm kind of sad that I wasn't able to play today. But I think in the end it's the right decision."