New world No.1 Naomi Osaka has pulled out of next week's Qatar Open with an unspecified back injury, tournament organisers said on Tuesday.
Osaka, who had been set play for the first time since her Australian Open triumph, has suffered back problems in the past.
"I am sorry to have withdraw from Doha this year as I was looking forward to playing and seeing my fans there," the 21-year-old said in a statement.
"I wish everyone a great week and hope to see everyone next year."
Simona Halep, the Romanian who Osaka replaced as No.1, Karolina Pliskova and Angelique Kerber head up the field from February 11 in Doha.
