Roger Federer [Images] has little time to rest on his latest laurel.

The 24-year-old Swiss took his Grand Slam tally to six by retaining his U.S. Open title with a four-set win over 35-year-old Andre Agassi [Images] on Sunday.

But unlike after his third successive Wimbledon [Images] triumph in July, when he took a month and a half off, the world number one has barely a week to prepare for an intriguing Davis Cup playoff tie against Britain.

Also Read Federer untouchable for now: Nadal Federer wrecks Agassi's dream Roger better than Pete: Agassi

The winners of the tie, which will be played in Geneva on clay starting a week on Friday, will secure their place in the elite World Group for 2006.

Having won a record 35th consecutive hardcourt match by beating Agassi on Sunday, Federer admits it will not be easy to adjust to clay.

The Swiss team chose to play the match on tennis's slowest surface because it is the one the British players are usually least comfortable on, even though it has also been Federer's least successful surface.

"All I want to do is get back in the World Group and the best chance I think was on clay," said Federer. "I'm putting myself through this strain of moving from one surface to the other because I want to help out my country as much as I can.

"We have more chance to win on clay than other surfaces when (British player) Greg Rusedski [Images] might be a little more dangerous. So I hope to take him a little more out of play with that."

MURRAY FACTOR

Federer admitted the Swiss team had not factored in the emergence of British 18-year-old Andy Murray at Wimbledon and the U.S. Open when they chose the surface. Murray trains on clay in Spain.

"We didn't know about Murray that well when we picked the surface," Federer said. "But no matter what surface you play on against Murray, he's become a great player throughout the last few months.

"It's tougher than expected all of a sudden. But I still feel like we're the big favourites.

"I still feel very fresh. I have reserves left in my tank."

Speaking in a sports bar on Times Square on Monday, the Swiss faced inevitable questions about whether his priority now was to reel in Pete Sampras's [Images] record of 14 grand slam wins.

At his current rate of two a year - he won both Wimbledon and the U.S. Open this year and last - he would match the American's mark by the age of 28.

"He is still far off. He's got some margin," Federer said.

"But I don't like just to look at the slams as the only thing that matters. For me it means the other tournaments, when I'm competing against the best players or playing in front of thousands of people, don't really matter. I don't like it.

"I have 32 titles and six of them are Grand Slams so you see the majority are other tournaments."

Perhaps the Swiss's most extraordinary record so far is his 23 consecutive wins in finals.

On Monday, though, he did offer a ray of hope for his opponents.

"You can't keep it up all the time. It's hard on you mentally and physically. It's a draining sport," Federer said.

"I expect myself not to be at the top at some point."

• Complete tennis coverage
• All you want to know about Sania Mirza