Andy Murray hits a return to Juan Martin del Potro on Sunday. (AP)

London: Andy Murray made home advantage count as he defeated US Open champion Juan Martídel Potro 6-3, 3-6, 6-2 in the opening singles match of the ATP World Tour Finals at London's O2 Arena.

Murray is competing at the prestigious eight-man event for the second time after reaching the semi-finals on his debut in Shanghai last year and dug deep to get his Group A campaign off to the perfect start.

Del Potro, who was won only two matches since his New York triumph in September, put in a very inconsistent display, with some scorching winners punctuated by simple errors.

The first set was a strange affair, Murray saving two break points in the opening game before going on to take a 5-0 lead.

Del Potro took a medical time-out after the third game to receive treatment to his face, but he was certainly struggling to find his range and some basic errors left the Scot barely able to believe his luck.

It was almost inevitable Del Potro's malaise would not last and, having saved two set points to avoid a whitewash, he retrieved one of the breaks before Murray finally clinched the opener at the eighth time of asking.

The Scot had won four of their previous five matches but the clashes have often been close and he would have expected the Argentinian to come out firing in the second set.

And that is exactly what transpired, a sloppy Murray service game allowing Del Potro to break to love then open up a 3-0 lead.

Murray broke back but soon dropped his serve again and Del Potro went on to level the match.

The home favourite was certainly not at his best and seemed to be struggling for rhythm, understandably so given the pattern of the match.

He recovered from 15-30 to hold serve in the opening game of the decider and finally got the crowd really behind him when he capitalised on a second break point to move into a 2-0 lead.

Del Potro rallied in the fourth game and then put his opponent under pressure with some more huge groundstrokes but Murray served well and sealed victory with a backhand winner after Del Potro had put himself in trouble with successive double faults.

Murray said: “It was always going to be tough. I played well today (Sunday), started really good, he came back into it but I stayed tough in the third set.”

Earlier, Murray reacted contemptuously to suggestions that he should play more aggressively in an attempt to regain his world No 2 ranking.

Greg Rusedski, the former British No 1, and Barry Cowan, best known for extending Pete Sampras to a fifth set at Wimbledon in 2001, have both claimed that Murray needs to attack more to become a Grand Slam champion — but their arguments drew a withering response from the Scot.

“Yeah, who are these 'experts?” Murray asked, rhetorically. "Barry Cowan? Greg Rusedski? I think I know more about tennis than Barry and Greg. I work very hard with my coaching team to come out with the right game plan. I've been told a lot of times that I'm very astute.

“You don’t get to be No 2 in the world at anything if you’re one-dimensional. If I go out playing ultra-aggressive and lose all three of my matches, people would say, ‘What are you doing?’

“Regardless of what people think, if I don't win a major tournament in my career I will still have enjoyed the way I played. I think it's different to what most other players are doing.”

In a week when his sport is trying to project its best image, Murray also drew a telling comparison with the controversy convulsing football after Thierry Henry’s handball for France, at the expense of the Republic of Ireland’s World Cup ambitions.

“The technology does make a difference,” Murray said. “Even in the US Open final this year there were over-rules being made from Hawk-Eye. It is up to the football authorities to decide but it does help in sport. Personally I like coming off court knowing that I didn’t lose through a bad call. But some people just seem to like controversy.”