On Friday night, the Garden of Ono was overrun by tennis balls and Heineken kegs to celebrate the U.S. Open kickoff. Like fillies just learning to walk, young lady tennis stars tottered around hesitantly, their knotty calves unaccustomed to stiletto heels. Men sporting blazers and bronzer gleefully spectated. "I really like [Rafael] Nadal," said Serena Williams, who was avoiding alcohol and snacks for the night. We tried to get her to dish on what happens in the stadium locker room, but she upheld an Open oath of omerta. "What happens there stays there," she said. "It’s kind of like Vegas." Her sister Venus, who sneaked in the back, kept incognito under a tennis cap (except to say hi to Kevin Connelly and Andy Roddick). We asked Serena what new girls we should look out for on the court. "You know everyone now is so young and so good," she said, shrugging. "And so … Russian."—Amy Odell