Maria Sharapova is realistic as she tries to regain her form after a 15-month drug suspension.

"I think no road is easy," Sharapova said Sunday before a World Team Tennis match.

Sharapova played for the Orange County Breakers in their season-opening match against the defending champion San Diego Aviators at the La Costa Resort and Spa. It was Sharapova's first appearance in the U.S. since testing positive for meldonium at the 2016 Australian Open.

She returned to the court in April and played three tournaments in Europe. In her first event, the Russian star reached the Porsche Tennis Grand Prix semifinals. A thigh injury prevented Sharapova from competing in the grass-court season that ended at Wimbledon on Sunday. But now she's fit and ready for a summer run, hoping to cap it at the U.S. Open.

"It's nice to have a schedule again and something that I really miss, having a tournament on the schedule and a calendar and knowing what I have to prepare for," Sharapova said.