Osaka, the 2019 and 2021 champion at Melbourne Park, was reduced to tears on Sunday when an abdominal injury forced her to quit while leading Clara Tauson 6-4 in her first WTA final in almost three years.
"I'm having an MRI today to assess," she said in a brief statement. "I don't feel that it's too serious and I still feel very optimistic about AO."
Osaka, who returned to the tour a year ago after a long maternity break, had shown glimpses of the form that won her four major titles on her run to the final in Auckland.
She broke back into the top 50 in the world rankings on Monday.
The Australian Open begins on Sunday.