Maria Sharapova beat Jennifer Brady 6-1 4-6 6-0 as she returned from injury at Stanford's Bank of the West Classic.
Sharapova, who returned in April after a 15-month doping ban, had been out with a thigh problem since 16 May.
The 30-year-old, given a wildcard to play in the United States for the first time since March 2015, was given a testing time in the first round.
"I feel like I just want to hug everyone and say thank you," said Sharapova, ranked 171st in the world.
"It's my first match in the States in a really long time, and it's the closest thing to home for me.