Maria Sharapova insisted she can consider 2011 a successful Grand Slam year despite being bundled out of the US Open by Flavia Pennetta in a third round shocker.
Italian 26th seed Pennetta stunned the third seeded Russian, who was the 2006 champion in New York, 6-3, 3-6, 6-4 in a two and a half hour epic on Arthur Ashe Stadium.
But Sharapova, who was one of the favourites for the title, slumped to defeat under the weight of an embarrassing 60 unforced errors and 12 double faults.
"I've had a much better year than last year. Obviously it's disappointing and it's not where I want to be, but it's the way it is. It's called tennis," said Sharapova.
In 2010, she failed to get beyond the fourth round of any of the four majors.
The world's highest-paid sportswoman, who won the last of her three Grand Slam titles in Australia in 2008, before her nine-month shoulder injury lay-off, became the latest big name casualty at the US Open.
After Sharapova's defeat, only five of the world's top 10 are still involved in the title race.
And the Russian, a finalist at Wimbledon and semi-finalist at the French Open, knows that she squandered a great opportunity to add to her three majors.
"It's disappointing. It's disappointing to lose in the middle of nowhere. It's disappointing to lose in New York. Losing isn't fun for anyone because we work to win. We don't work to try to lose," she said.
"It's tough. But it's all right. It was just one of those days. Unfortunately it was at the US Open.
"Sometimes I come in on a day and I don't quite have my rhythm, and run into those errors where not only do I feel like I have to get a high percentage of first serves, but my opponent gains a tremendous amount of confidence on their return. So it's kind of a lose/lose situation."
Sharapova had won all 12 of her three-set matches in 2011 before Friday, but there had been signs of struggles in her first round tie where she squeezed past British teenage Heather Watson despite committing 58 unforced errors.
Pennetta, a quarter-finalist in 2008 and 2009, goes on to face China's 13th seed Peng Shuai, the highest-ranked player left in that quarter of the draw.
The Italian has a 4-0 winning record against Peng.
"It's amazing. It's one of the best victories of my career," said 29-year-old Pennetta after the two and a half hour marathon.
"We both fought a lot and in the last set I was really nervous. I was 4-1 up and I was shaking a little bit, but now I am really proud of myself."