Rafael Nadal admits Roger Federer US Open clash may never happen

Rafael Nadal believes that facing Roger Federer at the US Open might have to remain just wishful thinking after the worrying decline of the Swiss superstar continued in New York.

Federer, the winner of a record 17 Grand Slam titles, fell to Spanish 19th seed Tommy Robredo 7-6 (7/3), 6-3, 6-4 in the fourth round, his earliest exit from the US Open in 10 years.

It also doomed hopes for a potential quarter-final match with 12-time major winner Nadal in what would have been the first meeting of the pair's 31-match rivalry at Flushing Meadows.

"To be honest, it's going to be great if we were able to play a final because I felt that in our rivalry for so many years we were able to play in all the best scenarios, stadiums, around the world," said Nadal, who reached the quarter-finals with a 6-7 (4/7), 6-4, 6-3, 6-1 win over Philipp Kohlschreiber.

The two men have played four finals at the French Open, three at Wimbledon and one at the Australian Open.

"We played the rest of the finals in the Grand Slams. So probably the rivalry deserves to have that match here in the US Open on the biggest court in the world," added Nadal.

"But it didn't happen. That doesn't mean it cannot happen in the future. We'll see. Hopefully. But is true that we are getting older, so the chances are less today than five years ago."

Nadal is only 27 but Federer has already turned 32.

Federer had made 36 consecutive Grand Slam quarter-final appearances before being upset by Ukrainian Sergiy Stakhovsky in the second round at Wimbledon this year, having not departed a major before the last eight since the 2004 French Open.

Monday's defeat also made this the first year since 2002 that he has not made a Grand Slam final.

It came out on Louis Armstrong Stadium where he had not played since 2006 as organizers relegated him from the showpiece Arthur Ashe arena following a four-hour rain suspension to the day's schedule.

Nadal, the US Open champion in 2010, took his 2013 record to 57 wins against just three defeats and his perfect hardcourt form to 19 victories since his return in February from a seven-month injury layoff.

As he looks forward to a clash with Robredo for a semi-final spot, he insisted that he had never got caught up in the hype surrounding a potential match-up with Federer.

"For two times we were one point away (from meeting in New York). But it is always the same, no? You (the media) make the confrontations before the draw.

"When the draw is coming and in the first round you always talk about quarter-finals. To be in the quarter-finals you need to win four matches. That's not easy for anybody."

Robredo, meanwhile, defeated Federer for the first time in 11 meetings and believes it would be foolish to write off the former world number one, who has now sank to seven in the world, his lowest level for more than a decade.

"Roger, when he was number one, compared to the Roger right now, he doesn't maybe have the same confidence," said Robredo.

"Obviously he's the same player and he plays unbelievable, but I knew that if I had a few more chances, maybe he will have a little bit of doubt."