NEW YORK – Novak Djokovic heard what Andy Roddick said about him and didn't like it one bit.

Still, as much motivation as Djokovic might have had, and as well as he played in their U.S. Open quarterfinal Thursday night, Roddick's uncharacteristic serving miscues had a lot to do with his 6-2, 6-3, 3-6, 7-6 (5) loss.

Two points from forcing a fifth set at 5-4 in the fourth, Roddick double-faulted twice in a row and was broken for the fifth time – twice more than he lost serve in his first four matches combined.

In Djokovic's previous match, a five-set ordeal Tuesday against No. 15 Tommy Robredo, Djokovic called for the trainer more than once as he dealt with hip, ankle, stomach and breathing issues.

Asked then about Djokovic's problems, Roddick kidded around, checking whether the list shouldn't also include bird flu, anthrax, SARS and a common cold and said: "He's either quick to call a trainer, or he's the most courageous guy of all time."

Roddick also said in an on-court interview that day: "I've got to feel good. He's got about 16 injuries right now."

After beating Roddick, ending the match with a 125 mph serve that drew a long return, Djokovic made reference to those comments.

"That's not nice, anyhow, to say in front of this crowd that I have 16 injuries and that I'm faking," Djokovic said during a postmatch interview that drew boos from the spectators in Arthur Ashe Stadium.

"They're already against me, because they think I'm faking everything."

Djokovic, the No. 3 seed, advanced to a semifinal against Roger Federer. It's a rematch of last year's U.S. Open final, which Federer won.

Djokovic is 2-6 against Federer and called him the "absolute favorite."

Federer puts away qualifier: As the break points and the set points slipped away, as his shouts of self-admonishment grew louder, it was hard to imagine Federer was having this tough a time in his U.S. Open quarterfinal against a man ranked 130th.

Fans used to watch Federer hoping to be awed by his brilliance. Now they wonder: Is he going to hang on?

For the most part, even during this poor-by-his-standards season, he does get by. Federer shook off missed opportunities to beat qualifier Gilles Muller of Luxembourg, 7-6 (5), 6-4, 7-6 (5), and extend his record by reaching the semifinals at an 18th consecutive Grand Slam tournament.

It was Federer's 32nd straight victory at the U.S. Open, where he has won the last four championships. The only man to have won more matches or titles in a row at this tournament was Bill Tilden in the 1920s.

Federer spoke proudly of his run of major semifinals; no other man ever topped 10.

"A huge streak," he said. "I hope this time around I can take it a step further than I did in Paris or Wimbledon."

See? Even he focuses on his missteps, making reference there to his losses to Rafael Nadal in the last two Grand Slam finals.

Nadal outlasts Fish: It sure took a while, but Nadal is a U.S. Open semifinalist.

Nadal, the No. 1 seed, got past the quarterfinals for the first time in six trips to Flushing Meadows, beating unseeded Mardy Fish, 3-6, 6-1, 6-4, 6-2.

The match ended at 2:10 a.m. Thursday, making it the third-latest finish in tournament history.

"This is one of the things that we players discuss all the time. There should be a limit on when to start. But we know that the TV rules in this," Nadal said.

Fish took the opening set on the strength of a 23-6 edge in winners, some gutsy serving and one service break. But Nadal never faced a break point the rest of the way.