MELBOURNE, Australia (AP) — Former Australian Open champions Naomi Osaka and Victoria Azarenka withdrawn from tuneup tournaments Saturday, two days before the year’s first tennis major begins at Melbourne Park.

No. 3-ranked Osaka pulled out of her Gippsland Trophy semifinal against Elise Mertens, citing a “niggling injury."

Azarenka withdrew from the Grampians Trophy quarterfinal match against Anett Kontaveit with a lower back problem.

Serena Williams withdrew from the Yarra Valley Classic late Friday after qualifying for a semifinal against top-ranked Ash Barty.

All international players and staff have been through two weeks of quarantine. Organizers put on six tournaments this week at Melbourne Park to give players time to prepare for the Australian Open, which has been delayed three weeks because of the COVID-19 pandemic.

U.S. Open champion Osaka and Serena Williams, who is chasing a record 24th Grand Slam singles title, are on the same half of the draw at the Australian Open.

“Sorry to Tennis Australia and the fans to have to withdraw today,” Osaka said. “I have a niggling injury and in light of the (Australian Open) on the horizon, I need to be cautious. I look forward to competing next week.”

Her withdrawal gives Mertens a walkover into the final.

The withdrawals forced a reshuffle of the order of play on Margaret Court Arena. Former champion Angelique Kerber was moved up to meet fifth-seeded Maria Sakkari.

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