Maria Sharapova has confirmed she has been forced to withdraw from the forthcoming Miami Open due to a forearm injury.

"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," she told the tournament's official website (h/t Sky Sports Tennis).

The news is the latest setback for the Russian, who has endured a tough time since returning from a 15-month doping ban in April 2017. 

The 30-year-old was knocked out of the 2018 Australian Open in straight sets by Angelique Kerber in the third round and has not managed a victory since that January defeat.

Sharapova was beaten in the first round of the Qatar Open by qualifier Monica Niculescu and then lost in the first round of Indian Wells to Naomi Osaka.

BBC Sport's Russell Fuller explained why she has been struggling:

The Russian announced after that defeat that she had also parted ways with coach Sven Groeneveld. The Dutchman had stuck with Sharapova throughout her long ban but has now been deemed surplus to requirements.

Tennis writer Ben Rothenberg expects Groeneveld to be in-demand but is uncertain about Sharapova's future:

Sharapova also withdrew from the Dubai Open in February due to an issue with her forearm, and it appears the injury is still causing problems. American Jennifer Brady will replace Sharapova in the draw for the Miami tournament.

The Russian's future does appear uncertain, as she is without a coach and is struggling for fitness and form.

She will turn 31 in April and may not continue for too much longer, according to sports reporter Matt Dowell:

Despite her withdrawal, the Miami Open still boasts a strong lineup, with Caroline Wozniacki, Venus and Serena Williams, Garbine Muguruza, Jelena Ostapenko, Sloane Stephens and Kerber all featuring.