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.

Former world No. 1 Naomi Osaka retired from the ASB Classic final in Auckland on Sunday due to an abdominal injury after winning the first set against Clara Tauson.

The former world No. 1 and four-time Grand Slam champion retired from the final of the WTA Auckland Open, the last tune-up before the Australian Open, with an apparent medical issue on Sunday. She had been leading Denmark's Clara Tauson 6-4 before her exit left Tauson as the tournament's champion.

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.

Osaka retired from the ASB Classic final in Auckland due to an abdominal injury. The four-time Grand Slam champion won the first set against Clara Tauson 6-4 before taking an immediate medical time-out that would signal the end of the match. Due to injury, Osaka has retired from the match. Clara Tauson is the champion with a final score of 4-6.

Former world No. 1 Naomi Osaka reached her first semi-final in almost three years after she came from behind to beat Hailey Baptiste 6-7(2), 6-1, 6-2 at the ASB Classic.

Naomi Osaka has made her first WTA final in three years and she is a win away from lifting her first title as a mom. On Saturday, the seventh-seeded Japanese ousted world No. 82 Alycia Parks 6-4 6-2 in the semifinal of the WTA 250 tournament in Auckland.

Naomi Osaka will undergo a scan on the injury that forced her to pull out of the Auckland Classic final but remains optimistic about playing at the Australian Open.