Maria Sharapova was knocked out of the U.S. Open in the third round on Friday after a 6-3, 3-6, 6-4 loss to No. 26 seed Flavia Pennetta of Italy.
The defeat was the 2006 champion's first loss in 13 three-set matches this year.
"She's a good fighter," said Pennetta, who conceded she didn't know about Sharapova's record in three-setters. "You can never give up with her. You have to be focused until the last game, until the last point, actually."
Sharapova made 12 double-faults, including two in the last game. She did not look sharp over a 2 hour, 29-minute match that featured plenty of nervous tennis. Sharapova made 60 unforced errors and lost four break points while trailing 2-0 in the third set.
"I didn't feel comfortable with most of my game today," Sharapova said.