San Francisco - Five-time Grand Slam champion Maria Sharapova withdrew from the WTA Bank of the West Classic just before her scheduled second-round match Wednesday with a left arm injury, tournament officials announced.
"We're sad to announce that @mariasharapova has withdrawn after doctor's advice regarding her left arm," a post on the tournament's Twitter feed said.
Sharapova played her first US match in more than two years on Monday, defeating American Jennifer Brady 6-1, 4-6, 6-0 in an opening-round match at the hardcourt event in Stanford, California.
The former world number one from Russia hadn't played in the US since March of 2015, before serving a 15-month doping suspension for the use of meldonium.
"I feel like I just want to hug everyone and say thank you," Sharapova told fans in a post-match interview. "It's my first match in the States in a really long time, and it's the closest thing to home for me."
Seventh-seeded Ukrainian Lesia Tsurenko advanced by walkover as a result of wildcard entrant Sharapova's early exit.
The latest injury brings into question whether or not Sharapova will be fit in time for the US Open, which starts August 28, as well as for another key tuneup event in Cincinnati in two weeks for which Sharapova has also accepted a wildcard.
Sharapova, 30, returned to competition in April, but her comeback was disrupted by a hip injury that forced her to withdraw from Wimbledon qualifying.
Sharapova's ranking has fallen to 171 in the world.
"I feel like I'm playing catch-up against everyone who has had a head start," Sharapova said after her Mondya match. "All that matters is that I keep playing."