Murray defeats Del Potro in Tour Finals opener

Andy Murray of Britain reacts after winning match point during his ATP World Tour Finals first round tennis match against Juan Martin Del Potro of Argentina in London November 22, 2009.

LONDON (Reuters) - Andy Murray marked the beginning of London's five-year hosting of the ATP Tour Finals with a 6-3 3-6 6-2 win over U.S. Open champion Juan Martin del Potro in front of 17,500 fans inside the spectacular o2 Arena on Sunday.

The Briton withstood a ferocious comeback by Argentine Del Potro, who lost the opening five games, to open his account in Group A which also contains world number one Roger Federer and Fernando Verdasco who play later.

After thumping rock music and swirling spotlights greeted the players on court, Murray won a nervy opening game by saving a break point with an ace before striding into a 5-0 lead as Del Potro's dynamite forehand failed to ignite.

However, the Argentine began to use his albatross-like wingspan to good effect as the set wore on and although Scot Murray finally clinched the opener on his seventh set point the tide had turned in the South American giant's favor.

Del Potro broke serve twice in the second set and after leveling the match with an unstoppable forehand he looked the more likely winner.

As quickly as it had sparked into life Del Potro's challenge withered in the decider after he dropped serve in the second game to hand the momentum back to world number four Murray.

A double fault gifted Murray two match points and he swiped away a crosscourt backhand to complete a victory that puts him on course for the semi-finals of the season-ending showpiece.

Group B action opens on Monday when Rafael Nadal, who can still beat Federer to the year-end world No.1 ranking, faces Swede Robin Soderling and Novak Djokovic takes on Nikolay Davydenko.

(Editing by Tony Jimenez)