And once again, Roger Federer is out prematurely at a Grand Slam. Federer was upset in the 4th round at the U.S. Open tonight to Tommy Robredo, 7-6, 6-3, 6-4. It was really sad to watch. The mystique of Roger Federer is vanishing as each crushing Grand Slam loss mounts one over the next. On break points tonight, Federer was an astoundingly poor 2 of 16. On some of those break point chances, he was bad as he's ever looked—backhands hit listlessly into the net, forehands ugly and wide. "I missed so many opportunities," Federer said after the match. Thanks to a hours-long rain delay this afternoon, the Federer-Robredo match was sent over to Louis Armstrong, the U.S. Open's no. 2 court. It was the first time Federer had to play there in seven years. The stadium had …