By Pritha Sarkar

NEW YORK (Reuters) - Rafael Nadal ducked out of his courtesy car on to the soggy grounds of Flushing Meadows at 11.30am, looked skywards to inspect the menacing clouds, shook his head and then dashed into the U.S. Open players' lounge.

Unfortunately for the Spaniard, the rain gods simply did not let up Friday -- it simply poured all day long - leaving the world number three to once again endure that sinking feeling.

For the second year running, Nadal finds himself having to play three days running if he is to win the one title he needs to complete a career grand slam. Throw in a abdominal strain that Nadal has been struggling with for a number of weeks, and his task becomes a 100 times more difficult.

While Roger Federer, Novak Djokovic and Juan Martin del Potro can look forward to twiddling their fingers Saturday having booked their places in the semis, Nadal will have to return to the National Tennis Center to complete his quarter-final against Fernando Gonzalez which began on Thursday.

Del Potro awaits the winner of the Nadal-Gonzalez contest.

"It can be hard to play back-to-back-to-back. A number of times it really affected me in matches," four-times U.S. Open champion John McEnroe told Reuters in a telephone interview.

"You see players not play up to their capability because they're spent. It's the last major, it's a very physical one. People are more beat up after playing the whole year.

"Look at Roger. He played Wednesday and doesn't have to play again until Sunday, same with Djokovic. That's an advantage to those guys, no doubt.

"They don't have the strain mentally of what Nadal's been through ... not only does he have this (injury) thing he's got to worry about, but sitting around takes a bit of a toll."

Just as in 2008, the final weekend of the U.S. Open has been thrown into disarray, causing both singles finals to be delayed by at least 24 hours. The backlog created by the rain means that the men's final cannot be staged before Monday.

With Friday's play completely washed out -- the first time since 2006 when a full day was lost -- Nadal could do little but look out of the window as he engaged his mind playing table football in the player's lounge.

No doubt sometime during the day, he must have thought, "Why me?"

Twelve months ago his semi-final against Andy Murray spilled over to a second day after organizers delayed the start of his match by several hours even though they knew the remnants of Tropical Storm Hanna were due to hit Flushing Meadows early in the afternoon. The forecast was spot on.

Although Nadal was spared having to play three days in a row as he was beaten by Murray, the toll such a schedule takes was all too evident when the Briton turned up for the final. Federer's fresher pair of legs easily carried him to a fifth successive title.

Nadal's battles with the weather go back even further as in 2007 he was forced to play seven days in succession at Wimbledon when rain badly affected the second week for the grasscourt championships. He too ran into a rested Federer in the final, only to lose the showpiece in five sets.

Thankfully, Wimbledon unveiled its new retractable roof this year to counter the problem and calls to build one over Arthur Ashe Stadium have been growing louder -- especially since the Open's unique scheduling over the final weekend leaves no room for error.

While all the other slams have a rest day for the players between the semis and the final, in New York they are contested over consecutive days.

"I know they say it doesn't rain as much here in New York as it does in London, for example... but now they're in a big hole," said McEnroe.

So is Nadal, who wore a worried look as he trudged out of the grounds almost seven hours after he arrived without hitting a ball.