Murray questions Cup

"I don't know exactly how long I will continue playing Davis Cup," Murray told the Guardian.

"I'm not going to just say I'm going to retire from it when I'm 21."

The 20-year-old Scot helped lead Britain to a victory over Croatia at Wimbledon in September and into the Davis Cup World Group in 2008.

Britain play Argentina in the first round of the World Group next month and Murray expects a difficult test in the team's first tie since Tim Henman retired from the sport.

"The Argentina match is a tough tie but I'm doing my best to make sure that I can schedule my tournaments around it so that I can play," said Murray, who begins his season against Belgian Olivier Rochus in Qatar on Tuesday.

"If there (were) a home tie straight after (the Australian Open) it (wouldn't) make sense for me to miss the tie.

"It's a pretty easy option just to play in Britain but, when it's an away tie, the last thing I want to be is on the tour and travelling here and there all over the place."

Murray, who sacked his American coach Brad Gilbert in the fall and will now travel with a rotating team of coaches and trainers, hopes to improve on his best season on the ATP Tour this year after finishing the 2007 season with his best end-of-year ranking at 11th in the world.

"I've said all along that the most important thing is to keep developing. I just think it's better for me to have a longer and more consistent career than to have a couple of great years and then fall off the radar," he said.

"I'm still developing physically a lot. I still think I can develop my game a lot. I'm only 20. In a lot of other sports it's like it's unbelievably young, give him a chance, let him take his time.

"But in tennis in Britain they want you to be winning from a really young age, which is fine but it's not exactly how I view it. I think I have done a lot of winning so far, at the highest level. I've been in the top ten already."

After an injury ravaged 2007, during which he missed three months but still came within one victory of reaching the season-ending Masters Cup, the British number one has made his primary goal for the upcoming season to remain fit.

"This year is an important year for me but if I don't finish number two or three in the world it's not a disaster as long as I keep improving.

"And if I'm improving my ranking's going to get better, so I'll just keep hopefully playing like I did last year and hopefully be in better physical shape. If I'm in better physical shape and I'm playing like I did last year then I'm going to have more consistent results.

"The most important thing is not to start thinking about my ranking first and start chasing points all over the place.

"It's to keep developing my game and improving my fitness and hopefully by improving those things my ranking's going to get better."