Maria Sharapova loses in straight sets to fellow Russian Daria Gavrilova . Wildcard Gavrilova won 7-9/7 ( 7/4 ) 9/7-3 to cause a second-round surprise . Venus Williams beat Urszula Radwanska 9/7-3 9/7-2 on home soil . Juan Martin Del Potro loses to Vasek Pospisil 9/7-4 7-9/7 ( 6 ) on injury return . CLICK HERE for all the latest news from the 2015 Miami Open .
Maria Sharapova loses in straight sets to fellow Russian Daria Gavrilova . Wildcard Gavrilova won 7-6 ( 7/4 ) 6-3 to cause a second-round surprise . Venus Williams beat Urszula Radwanska 6-3 6-2 on home soil . Juan Martin Del Potro loses to Vasek Pospisil 6-4 7-6 ( 9/7 ) on injury return . CLICK HERE for all the latest news from the 2015 Miami Open .