Jennifer Capriati recovered from a sluggish start to beat Russian teenager Maria Sharapova 5-7, 6-4, 6-1 on Thursday and reach the quarter-finals of the German Open in Berlin.
Sharapova, 17, confirmed her potential by giving Capriati a hard time but the American, seeded sixth in the claycourt tournament, stepped up a gear after a losing a tight first set.
"I felt I played a very decent match but she's been in such situations where a match is close many times before and knows how to deal with it," said Sharapova, who bowed out by hitting a forehand long on match point.
Capriati goes on to meet fourth seed Anastasia Myskina of Russia, who qualified the easy way when Swiss Patty Schnyder withdrew before their third round match because of a left arm injury.
"She (Sharapova) played well but I'm also to blame because I didn't play my best tennis in those first two sets," said Capriati, making her ninth appearance in Berlin, where she reached the semi-finals as a 15-year-old in 1991.
"I fought very hard and my fitness was obviously a factor, added the 2001 French Open champion.
The 28-year-old has struggled with persistent back pain this season and is looking for a good run here to boost her confidence before the Paris Grand Slam starts on May 24.
Sharapova kept making her trademark grunt, living up to her reputation as the loudest player since Monica Seles.
"It's just a sound that comes out of my mouth," she said. "I know I'm doing it but I don't know why I do it."