Andy Murray gave the O2 Arena a big thumbs up after opening his Barclays ATP World Tour Finals campaign with an impressive victory over US Open champion Juan Martin del Potro.

With a capacity of 17,500, the venue is substantially bigger than Wimbledon's Centre Court and the British number one hailed the home support after battling to a 6-3 3-6 6-2 victory in the opening singles match to put himself at the top of Group A.

"It was great," said the 22-year-old. "It's different. You can't see the crowd when you're on the court, it's so dark. But you obviously hear them."

He added: "When I got close to winning at the end of the match, the atmosphere was excellent. That's going a make a big difference going into the next couple of matches."

Del Potro has won only two matches since his New York triumph - he, like Murray, has been hampered by a wrist injury - and his inconsistency was a feature of the match.

Murray raced into a 5-0 lead but the Argentinian hit back strongly and the world number four frequently found himself chasing down Del Potro's trademark huge groundstrokes.

The 21-year-old appeared to have the momentum going into the decider but a sloppy game allowed Murray to take an early advantage and he sealed victory with another break, capitalising on successive double faults before powering a backhand winner on match point.

Murray continued: "It was a really good start. Obviously I'm happy I managed to come back in the third because he was playing well."

Del Potro knows he now faces an uphill struggle to reach the semi-finals but he can see positive signs. "I feel good," he said. "I'm starting to play better. Maybe I get the confidence again to finish a good tournament here. But I have very good opponents in front of me."