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's quest for a first title in four years ended in heartbreak as the former world number one retired with an injury after winning the opening set of the Auckland Classic final against Denmark's Clara Tauson on Sunday.