NEW YORK -- Sara Errani didn't feel like a big favorite at the U.S. Open, even though her seeding said she was.
On Thursday, against her friend and Italian teammate, she lived down to her expectations.
Flavia Pennetta ousted fourth-seeded Errani from the year's last major, 6-3, 6-1 in the second round for the biggest upset of the tournament so far.
It was a loss Errani all but admitted she could see coming after she began her tournament with a 6-0, 6-0 blanking over a 152nd-ranked "lucky loser" on Tuesday. Afterward, she spoke of the pressure of being seeded so highly. She is, in fact, the highest-seeded Italian woman ever at a Grand Slam tournament.
"Definitely, from the outside, everyone expects a lot," Errani said. "Everyone expects me to win 6-0, 6-0, or thinks that I can only lose against three other women in this tournament. But that's not the way it is. I definitely don't feel like a big favorite, the way other top seeds might be."
ACE™ Brand Pressure Point of the Match: Already up 5-1, Pennetta continued to confound her countrywoman with a perfect lob after a series of defensive gets at 15-all. She wouldn't win the game, but it signaled her strong form that was enough to oust the No. 4 seed on Ashe.
Playing in half-empty Arthur Ashe Stadium, Pennetta took control of this match by breaking Errani's serve in the first game, then never looked back. She finished with 33 winners to 12 for Errani, who made the semifinals here last year after reaching the final in the French Open.
Pennetta improved to 4-2 lifetime against Errani. At 31, Pennetta is five years older than her Italian Fed Cup and Olympic teammate, and she is no stranger to the big stage.
Four years ago, Pennetta became the first Italian woman to crack the top 10. She's a three-time quarterfinalist at the U.S. Open but came to Flushing Meadows this week an underdog -- ranked 83rd, a slide that began when she missed the end of last year with a wrist injury.
"I tried to play aggressive from the very beginning and I was perfect today, I think," Pennetta said.
It was an unusually quiet match between the friends, who have been together on an assortment of Italian teams since 2008.
"When you play against one of your best friends, it's not easy to say `C'mon!' really loud," Pennetta said. "You just try to stay inside yourself."
Errani, whose serve topped out at 86 mph and whose game is based on getting lots of balls back from the baseline, has only made it past the second round in one of four majors this year, the French Open.
She says the increased expectations that come with success have pushed the tension "through the roof."
"This year, I'm not sleeping that well," she said. "Above all, I'm maybe approaching the Grand Slams in the wrong way. But I really get a sense of how difficult it is to handle everything sometimes. I ask myself how the strongest players handle it all. `'
Elsewhere in early play around Flushing Meadows, Errani's doubles partner, No. 10 Roberta Vinci, defeated Lucie Safarova of the Czech Republic, 4-6, 6-1, 6-2 and this year's Wimbledon runner-up, 16th-seeded Sabine Lisicki, defeated Paula Ormaechea of Argentina, 6-2, 6-3.
The Lisicki match and seven others were rescheduled for Thursday after rain washed out much of Wednesday's action.
Top-seeded defending champion Serena Williams took the court after Pennetta for a rescheduled match against Galina Voskoboeva.
Also due to play Thursday were Roger Federer, Rafael Nadal, David Ferrer and 17-year-old American Victoria Duval, who knocked out 2011 champion Samantha Stosur in a dramatic three-set match Tuesday.