Flavia Pennetta ended third seed Maria Sharapova's hopes at the US Open with a 6-3 3-6 6-4 win in the third round.
Zvonareva made to work hard for victory over Medina Garrigues
Flavia Pennetta ended third seed Maria Sharapova's hopes at the US Open with a 6-3 3-6 6-4 win in the third round.
The Russian, who triumphed in New York back in 2006, paid the price for 12 double faults and 60 unforced errors on Arthur Ashe Stadium.
Having been given a tough test by Britain's Heather Watson in the opening round, Sharapova could not find a way to battle through another stern challenge to become the first big-name casualty in this year's tournament.
The 24-year-old dropped her serve twice in succession to trail 4-0 in the first and although she put together a run of three straight games, retrieving both breaks in the process, her serve failed her again to go 5-3 behind.
However, Sharapova looked to be finding some form at the start of the second, easing 3-0 ahead. Four successive breaks of serve kept the third seed in front and she finally held to level the match.
Pennetta, a quarter-finalist in 2008 and 2009 in New York, held serve at the start of the decider and then was gifted a crucial break when Sharapova sent down an eighth double fault.
Serving issues
It was the serve that eventually knocked out the former champion too, starting with two double faults at the start of a game she had to win to stay alive.
A terrific forehand from Pennetta put her to the brink of victory and the Italian sealed a stunning result with a crunching backhand winner, setting up a fourth-round clash against China's Shuai Peng.
Sharapova admitted afterwards that she had paid a dear price for an error-strewn performance in blustery conditions.
"I made way too many unforced errors," she said. "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."
Vera Zvonareva was also pushed hard in her third-round match at Flushing Meadows, the second seed eventually getting past Anabel Medina Garrigues.
The Russian, who lost to Kim Clijsters in the final 12 months ago, edged a tight first set and then let a break lead slip away in the second before hitting back to win 6-4 7-5 in exactly two hours.
Romania's Monica Niculescu and Angelique Kerber of Germany will face each other next after both reached the fourth round of a grand slam for the first time.
Niculescu was particularly impressive, demolishing 27th seed Lucie Safarova 6-0 6-1, while Kerber defeated Alla Kudryavtseva of Russia 6-3 6-1.
Night session
In the night session, ninth seed Samantha Stosur won an epic battle with Russia's Nadia Petrova 7-6 (7-5) 6-7 (5-7) 7-5 on Louis Armstrong Stadium.
Both players had chances to win the match but it was the Australian who finally took it after three hours and 16 minutes.
And there was to be no fairytale for US teen Christina McHale, who beat eighth seed Marion Bartoli in round two but found 25th seed Maria Kirilenko too strong under the lights on Arthur Ashe, the Russian winning 6-2 6-3.
