By Julian Linden
NEW YORK (Reuters) - There is a familiar but deceiving look about the main contenders set to battle for the U.S. Open men's singles title when the year's final grand slam gets underway on Monday.
If history and current form are any guide, only five men - Roger Federer, Rafa Nadal, Novak Djokovic, Andy Murray and Juan Martin Del Potro - have any real chance of wearing the hardcourt crown.
Since the 2005 French Open, only five men have won grand slam singles titles but rarely have all five been in contention at the same event.
But this time they are and the U.S. Open is the one grand slam where they all believe they have a chance.
In the past five years, there have been five different winners at Flushing Meadows.
Unsurprisingly, they are the same familiar faces contending this year and the stakes could not be higher with all five desperate to prove a point.
For Federer, who won the title five times in a row from 2004-2008, it is looming as possibly one of his last chances to prove he is not a spent force.
The Swiss master may be the most prolific grand slam winner of all time but he has struggled in recent years, winning just one of the last 14 majors.
He still strikes the ball as sweetly as anyone but at age 32, he is not as nimble as his younger rivals and has started to slide down the rankings.
Federer is seeded seventh this year and facing a treacherous path to the final, including a possible quarter-final showdown with his old nemesis Nadal.
The Spaniard won the U.S. Open in 2010 to complete his collection of grand slam titles but the effort took a toll on his body.
Apart from the French Open, where he remains virtually unbeatable, Nadal has not won any other grand slam title since the 2010 U.S. Open, stalling his chances of overtaking Federer's record of 17 grand slam title.
Nadal already has 12 grand slam titles but hardcourt looms as the key to his chances of overtaking Federer with two of the four majors played on the pavement.
Unlike clay, where he can slide around and wear down his opponents with his relentless pursuit of everything hit at him, Nadal has to change his game on hardcourt.
The 27-year-old has to play more aggressively and take more risks to shorten the points but it is a strategy he is becoming more comfortable with and finding success.
This year he captured three of the four Masters events played on the North America hardcourts, including this month's tournaments at Montreal and Cincinnati, and heads into the U.S. Open as the slight favorite, just ahead of Djokovic and Murray, last year's finalists.
Djokovic has played in four of the last six U.S. Open finals but the world number one can count only one title.
Forced to live in the shadows of Federer and Nadal for many years, the Serb has been making up for lost time, winning six grand slam titles, a feat which already ranks him among the greats.
Like Djokovic, Murray has also had to wait for his turn but the Scotsman is at the peak of his game. Twelve months ago, he beat Djokovic in a five-set thriller to win the U.S. Open, becoming the first British man to capture a grand slam in 76 years.
He reached his crowning glory in July when he won Wimbledon and although he hasn't won a title since, he looms as a real threat to defend his title.
Del Potro won the U.S. Open in 2009 and was instantly hailed as the sport's new star before his career was stalled by injuries.
But the towering Argentine is finally back to full fitness and steadily climbing up the rankings, adding another contender to the mix.
(Reporting by Julian Linden; editing by Steve Keating)