The 29-year-old, who won Wimbledon and took gold in the Rio Olympics in 2016, replaced Djokovic as the top-ranked player two weeks ago, but would have relinquished the top spot had he lost.

After Murray recovered from serving a pair of double faults in his first service game, defeat never looked likely. The Briton made the most of his opportunities and refused to ease up, despite a gruelling semifinal against Milos Raonic just one day earlier. Murray broke his Serbian opponent in the second game, much to the delight of an 18,000-strong crowd in London that included Bastian Schweinsteiger and his wife Ana Ivanovic, a former world number one herself.

Murray then held serve nervelessly, converting his first set point to take a lead that he wouldn't relinquish.

Djokovic struggled to impose himself throughout, making 30 unforced errors, whilst Murray was ruthless in punishing an opponent against whom he has generally struggled. Murray broke in the first game of the second set before breaking again to take a 4-1 lead. Djokovic got one break back but it wasn't enough - the regulation forehand he skewed wide to hand Murray the win was typical of his performance. 

The win was Murray's 24th consecutive victory, his fifth consecutive title and the first time he has beaten Djokovic indoors after four previous losses. He paid tribute to the man he replaced at number one after the match.

"It's very special playing against Novak in a match like this. We've played Grand Slam finals and Olympic finals before, but I am very happy to win and to be world number one is very special. It is something I never expected," he said.

"My team have been around a long time, and my family have been there from the very start and made lots of sacrifices so I thank them.

"Me and Novak are lucky to have two great champions in our boxes, but to have other great champions like Mats Wilander and Stefan Edberg here today is special. To hold all four Grand Slams like Novak did this year was a very special achievement and something we won't see for a very long time."

Murray becomes the 17th man to hold the prestigious year-end number one berth since the inception of the ATP rankings in 1973. He is the first player other than Djokovic, Roger Federer or Rafael Nadal to earn the honour since Andy Roddick in 2003 and he also claimed prize money of just over a million euros ($1.06 million).

mp/mf (Reuters/AFP)