Five-time Grand Slam champion Maria Sharapova has withdrawn from Stanford’s Bank of the West Classic before her scheduled second-round match.
Tournament officials said the 30-year-old had pulled out on her doctor’s advice due to a left arm injury.
It means Ukraine’s Lesia Tsurenko has progressed in California.
Sharapova, given a wildcard to play in the US for the first time since March 2015, had defeated Jennifer Brady 6-1 4-6 6-0 on Monday.
The Russian had previously been out with a thigh problem since 16 May.
Sharapova returned in April after a 15-month doping ban, but was denied a wildcard for the French Open earlier this year and was unable to take part in qualifying for Wimbledon because of injury.
Having missed the entire grass-court season, she will not gain direct entry into the US Open, which starts on 28 August.
Sharapova will be eligible for qualifying but will need a wildcard from the United States Tennis Association if she is to automatically make the main draw. (Courtesy BBC)