Naomi Osaka suffered an injury concern on the eve of the Australian Open, but the four-time major winner has moved to allay fears over her fitness.

Last week, Osaka reached her first final since losing to Iga Swiatek in Miami in 2022, but the 27-year-old was forced to retire hurt from the clash with Clara Tauson.

Osaka won the opening set 6-4 on Sunday, only to withdraw after consulting with her trainer.

However, the two-time Australian Open champion is confident she will be fully fit by the time the season's first major starts on January 12.

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"I'm having an MRI today to assess," she said, as reported by Reuters.

"I don't feel that it's too serious and I still feel very optimistic about [the Australian Open]."

Osaka's efforts in New Zealand saw her rise up to 50th in the WTA rankings.