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.

"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.