Osaka, Krejcikova pull out of Dubai Championships.

Naomi Osaka, a four-time Grand Slam champion, and Barbora Krejcikova, the holder, have withdrawn from the Dubai Tennis Championship.

Osaka is still adjusting to life on tour after returning from a maternity leave last month.

The Japanese player lost in the first rounds of the Australian and Abu Dhabi Opens, as well as the Qatar Open quarterfinals to Karolina Pliskova on Thursday.

"I'm really sorry that I have to withdraw from the Dubai Tennis Championships this season," Osaka, whose last appearance in the event was five years ago, said in a statement on the tournament's website.

Former French Open Krejcikova champion, who won her first Dubai title last year by defeating world number one Iga Swiatek in straight sets, pulled out due to a back injury.

"This decision wasn't easy, especially given my fond memories and anticipation to compete again. However, my back injury requires further healing time. But I am committed to returning stronger next year," the Czech 28-year-old said.

SportsLigue