Murray says his best years can still be ahead of him

Andy Murray believes the best years of his career could still be ahead after confirming his status as world number one by beating Novak Djokovic to claim the ATP Tour Finals crown on Sunday.

Murray, 29, became the oldest man since 1974 to reach the top of the rankings for the first time last month and the way he dominated the final months of the season, winning five titles and 24 matches in a row, suggests he could be right.

"I obviously want to try and achieve as much as I can these next few years because I'm not going to be around forever," Murray, who won a second Wimbledon title and the Rio Olympics this year, told reporters after his 6-3 6-4 win at the O2 Arena.

"These next few years, I want to try and make them the best of my career. But it's going to be tough."

Had Murray lost to Djokovic on Sunday and relinquished top spot two weeks into his reign the chances are he would have overhauled the Serb again next year as he has fewer ranking points to defend in the months after the Australian Open.

Having scaled the summit earlier than he expected, Murray may well take some shifting.

"I would like to try and stay there. It's taken a huge effort the last five, six months," he said.

"I'm aware that's going to be extremely difficult. But now that I've got there, I obviously would be motivated to try and stay in that position.

"But the majors are what gets me working hard and what really, really motivates me."

First, however, Murray will afford himself the luxury of a short rest after a gruelling week in London where he twice set a new record for the longest match in the tournament's history.

On Saturday he spent three hours 38 minutes defeating Canada's Milos Raonic, having beaten Kei Nishikori in another three-hour epic in the group stage.

He admitted he was running low on energy late on against Djokovic as the Serb staged a late rally.

"I didn't feel great this morning. The practice, the warm-up for the match, I was hitting the ball fine, but just a bit sluggish, a bit heavy-legged," Murray said.

"Thankfully the first sort of seven games of the match, there was no long rallies, which for us is strange. It wasn't until the middle of the second set when the rallies started to get extended and longer that my legs were starting to feel it.

"I knew that the longer the match went, the worse I was going to feel, and probably the better he was going to play.