Maria Sharapova has withdrawn from next week's Miami Open because of a left forearm injury.
It has been a troubled season so far for the former world No 1, who has not won a match since the Australian Open having lost in the opening round in Doha and last week in Indian Wells.
After that defeat by Naomi Osaka, she parted ways with coach Sven Groeneveld, who had stuck with her through her 15-month doping ban, while she pulled out of last month's tournament in Dubai, also with a forearm problem.
In a statement on the official Miami Open website, Sharapova said: "I am really sorry that I have to withdraw from one of my favourite tournaments with my left forearm injury. I am doing everything possible to return to the tour as soon as possible."
The 30-year-old returned from her suspension last April but has struggled to make an impact at the top of the game and is currently ranked 41.
Sharapova, who has yet to win a title this year, will be replaced by American Jennifer Brady in the Miami tournament, which is scheduled for March 21 to April 1.
"We were looking forward to seeing her play Wednesday, but unfortunately injuries are part of the game. We hope she recovers quickly and is back on the court soon," Tournament Director James Blake said.
Top men's players, including Rafa Nadal, Stan Wawrinka and Dominic Thiem, have also withdrawn due to injuries.
