Roger Federer left to brood on why he missed out on blue riband final

So used to playing in the final at Flushing Meadows, the five-times champion left earlier than usual after Novak Djokovic got in the way of a much anticipated Rafa vs Roger title match at the US Open.

Djokovic prevented what would have been the eighth Grand Slam championship match between tennis' top two men - and first such showdown at Flushing Meadows - by coming back to stun Federer 5-7, 6-1, 5-7, 6-2, 7-5 in Saturday's semi-finals. "They all pretty much feel the same. They feel somewhat empty at the end, because you have tried everything - and maybe it was luck. Maybe it was he played well. Maybe you didn't pick the right shot. Maybe he did," said Federer, who had won 45 of his previous 46 matches at the US Open, reaching six consecutive finals.

"You feel like you left something out there if you lose a match having had match point," Federer added. "It wasn't a final, so I'm not as disappointed if it would have been a final."

His loss means that the third-seeded Djokovic was due to stand between No 1 Rafael Nadal and a career Grand Slam in last night's final which was delayed by rain. Nadal has eight major titles but had never been past the semi-finals at the U.S. Open before beating No. 12 Mikhail Youzhny 6-2, 6-3, 6-4 on Saturday.

Nadal will be bidding to become the first man since Rod Laver in 1969 to win the French Open, Wimbledon and the U.S. Open in the same season."I won't watch," Federer said, "but I hope he wins." Federer's record 16 Grand Slam titles include the 2004-08 US Opens, but he repeatedly let leads slip away against Djokovic. Federer took the first set, then the third. Even after Djokovic forced a fifth set, Federer twice was a single point from winning. "One of those matches," 2008 Australian Open champion Djokovic said, "you'll always remember."

For Federer, Saturday's setback came after losses in the quarter-finals of the French Open and Wimbledon, and he closes the 2010 Grand Slam season having played in one major final - the first year since 2003 that he hasn't reached at least two.

Federer's 3-hour, 44-minute loss to Djokovic was by far the day's best match, much more entertaining than the men's semi-final that preceded it. Nadal dominated with his serve again, holding 13 of 14 times.

"After a lot of work," said Nadal, who hasn't dropped a set these two weeks, "I am here in the final." In 2008, he lost in the semi-finals to Scotland's Andy Murray, and now says he was wiped out mentally after a long, if ultimately successful, summer that included a gold medal at the Beijing Olympics.In 2009, he lost to eventual champion Juan Martin del Potro, while dealing with achy knees and a torn abdominal muscle.

"For sure it's a very important victory for me," Nadal said. "To be in the final of the last Grand Slam of the year is something new." This year he took three weeks off after Wimbledon, skipping Spain's Davis Cup quarter-final to get knee treatment.