World No. 1 doubles team of Roberta Vinci and Sara Errani was upset by the Australian duo of Jarmila Gajdosova and Ajla Tomljanovic in the second round of the U.S. Open women's doubles in Flushing Meadows on Saturday.

The defending Wimbledon champions were immediately put against the wall as they were defeated in the first set with a break but the 2012 U.S. Open women's doubles winners fought back in the second set to force a tie-breaking set.

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The Australian team settled down on the third set to claim a third round spot, 6-4, 1-6, 6-4, in a match that lasted in just a little over two hours.

Gajdosova and Tomljanovic will face another upset winner of Martina Hingis and Flavia Pennetta who defeated 15th seeds Anastasia Pavlyuchenko and Lucie Safarova, 6-3, 6-0.

Pennetta is seeded 11th in the singles tournament and have advanced to the fourth round after defeating wild card entry Nicole Gibbs. She faces Australian Casey Dellcqua next.

"Flavia is a great partner to have," Hingis said. "She's been playing well in the singles ... I'm very fortunate to have her by my side."

The Italian defeat might be a backlash from Vinci's defeat against Peng Shuai in the singles competition Friday. Vinci probably couldn't keep up with the everyday schedule of play which resulted into their unfortunate early exit.

The 13th seed Errani, however, still has high hopes for a title at the singles event where she defeated Venus Williams in an unusual match, 6-0, 0-6, 7(7)-6(5), and now faces Croatian qualifier Mirjana Lucic-Baroni in the fourth round.

Lucic-Baroni upset second seeded Simona Halep Friday en route to a showdown with Errani on Sunday.

"She's playing very good if she won against Halep," Errani said. "Have to concentrate and try to keep on with my game."

This is Errani and Vinci's only Grand Slam tournament of the year that they haven't been able to reach the finals.

TagsSara Errani, Mirjana Lucic-Baroni, Flavia Pennetta, Peng Shuai