Quarterfinal Opponents Meet in Doubles First Playing in front of 235 spectators and 5,850 empty seats Tuesday, Italy's Sara Errani and Roberta Vinci, the No. 1 doubles team, defeated Flavia Pennetta, also of Italy, and Anabel Medina Garrigues of Spain, 6-1, 7-5, in a third-round match at the United States Open. The stands will most likely look different when Vinci plays Pennetta in a singles quarterfinal Wednesday at Arthur Ashe Stadium. "We know each other very well," said Pennetta, who is ranked No. The match from today was one of the hundred we've played already, so it's not gonna change a lot. Vinci and Pennetta played frequently as juniors in their home country, she said. Asked if she was confident of winning, Pennetta said: "No, I'm not. Because I think it's not easy. I'm not confident I'm going to win. I will try and I will do my best, but I'm not sure. Pennetta and Vinci have split their eight matches on the WTA Tour. Their last meeting came three years ago, when Pennetta defeated Vinci, 6-1, 6-1, in the second round of the French Open. A lot of things change. She's better, much better now," Pennetta said. Asked if she thought Vinci was the better player, Pennetta said, "At this moment, yes, she is." Vinci is ranked 13th but seeded 10th at the Open. Both players declined to say whether their doubles encounter had uncovered any weakness they might attempt to exploit Wednesday. In the doubles quarterfinals, Errani and Vinci, the defending Open champions, will face the winner of Wednesday's match between Serena and Venus Williams and the 11th-seeded team of Anastasia Pavlyuchenkova and Lucie Safarova.