Maria Sharapova has claimed that an error-strewn performance was behind her exit from the US Open at the third round stage.

The number three seed lost 6-3 3-6 6-4 to Italian Flavia Pennetta on the Arthur Ashe Court yesterday.

After the match, Sharapova bemoaned her failure to take the opportunities that were presented to her throughout the match.

"I made way too many unforced errors," she told reporters. "I fought back to get myself back in the match in the third set. I think the first three, four games, on every game I had a chance to win that game, whether it was a break point or it was a game point on my serve, and I didn't win those games.

"When you're down 1-4 and you get yourself back in a position where you can win again and then start making errors, it's just too inconsistent to win the match against her."

Sharapova won the US Open in 2006.