Miami  - Russians Maria Sharapova and Nikolay Davydenko both withdrew on Friday from next week's Miami Masters with injuries as the American hard court season moves to its second major event of the month.

Sharapova, who underwent shoulder surgery last October, tried and failed to test her shoulder with doubles last week at Indian Wells, California, losing in the first round with partner Elena Vesnina.

Her return to the WTA now looks to be put back to Rome on clay in May.

Davydenko, who has played just four matches since January 1, will be unable to defend his men's title due to the foot problems that have plagued him all season.

Sharapova, who has a massive global sponsorship contract with tournament and women's tour sponsor Sony-Ericsson, will make a promotional appearance at the title event where she has not played since 2007.

She is then scheduled to return to a clinic in Arizona where she has been rehabilitating her right shoulder.

"It felt great to be back on tour last week even if it was just playing doubles," said the three-time Grand Slam champion. "But I'm still not ready to play so many consecutive matches and will have to withdraw."

Play at Crandon Park, Florida, begins on Wednesday. (dpa)