Naomi Osaka's Australian Open campaign has taken on an element of doubt after the four-time Grand Slam champion and former No. 1 suffered an apparent injury Sunday while playing the final of a WTA tournament in Auckland.

Osaka had won the first set of the final 6-4 against Denmark's Clara Tauson when she spoke to her coach Patrick Mouratoglou, the chair umpire and a tour trainer before deciding to withdraw.

The nature of her injury wasn't immediately clear but seemed to be abdominal, not the back injury she suffered at the China Open in October and which ended her 2024 season.

Osaka was in tears as she sat waiting for the trainer. She then left the court to a subdued ovation as spectators before returning for the prizegiving.

“I've enjoyed playing here and I'm sorry it had to end this way,” Osaka said.

Osaka had led 5-1 with two breaks of serve when she began to look tighter, with less power in her serve. She managed to take out the first set before indicating she couldn't continue.

Osaka returned to tennis at the start of 2024 after a lengthy break following the birth of her daughter Shai.

The Auckland final was her first since her return to tennis and had she won, it would have been her first title of any kind since the 2021 Australian Open.