British hope Andy Murray made a strong start to his Barclays ATP World Tour Finals campaign Sunday in front of home support at The O2 in London. The Scot defeated US Open champion Juan Martin del Potro 6-3, 3-6, 6-2 in front of a sell-out crowd of 17,500 people to move to the top of Group A.

"When I got close to winning at the end of the match, the atmosphere was excellent," said Murray of the capacity crowd on centre court at The O2. "That's going a make a big difference going into the next couple of matches."

World No. 4 Murray had said at the media round tables on Friday that he did not expect to “play great” this week after limited match play in the past three months and the first Group A match featured highs and lows for both players.

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As del Potro struggled to find his range in the early stages of the pair’s sixth meeting, Murray was quick to settle into his rhythm from the back of the court and made few errors, in contrast to his Argentine opponent. With del Potro’s renowned forehand lacking its usual potency to end points, Murray was able to transition well from defence to attack and took his opportunities to carve out an early 5-0 lead.

Del Potro began to overcome his nerves at the close of the first set and forced Murray to require seven set points over the final four games as he recovered one of the service breaks and earned some confidence ahead of the second set. The Tandil native came out firing to create an early 3-0 lead and did not lose his focus when Murray scrambled the break back, rifling forehands at the Scot to quickly regain his advantage at 4-2. del Potro continued to pummel the Murray backhand with stinging forehands and the tactic paid dividends as he levelled the match.

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Murray was quick to involve the partisan crowd in the deciding set and, buoyed by their raucous support, took advantage of passive play from del Potro to lead 3-0. Murray, in turn, stepped up the court to dictate the points, keeping del Potro’s menacing forehand at bay. A deflated del Potro committed two double faults in the eighth game to trail 15/40 and Murray converted his second match point with a backhand winner after two hours and 10 minutes.

"Me and Juan haven't played that much since the US Open. I kind of expected a little bit of a scrappy match maybe," said Murray. "He didn't start particularly well, but after 5-0 (in the first set), I thought the standard was very good. Played some great points. Obviously happy to get the win.

"Tactically, I've always been quite good. So I found a way through it today. He does have a big forehand. He can hit a lot of winners; he can make mistakes off of it. There was a period [from the] end of the first set till the beginning of the third where he was hitting it big. I managed to keep myself in the point with sort of low slices and backhands, up the line. They helped a lot to kind of keep him out of that backhand court a bit."

“Against Andy, always the match is very tough,” explained del Potro. “We play three sets in every tournament, every match. Today was a little strange, but he played great tennis in the third set. He was a little lucky, but you need the luck to win and today it was with him. We had a very good atmosphere, very good crowd. Many Argentinians come to watch this tournament. So I'm very, very happy to be part of the eight players."

Murray improved to a 5-1 career lead over del Potro with his third win of the year over the Argentine. He also defeated del Potro in the semi-finals at the Sony Ericsson Open in Miami and the final of the Rogers Cup in Montreal – both ATP World Tour Masters 1000 tennis tournaments. Del Potro recorded his lone victory over Murray on clay at the Mutua Madrilena Madrid Open in May.

The 22-year-old Murray leads the ATP World Tour with six titles in 2009, triumphing most recently at the Valencia Open 500 following a six-week injury-enforced break. The Dunblane native, who has compiled a 65-10 match record, is looking for his second title on home soil after ending a 71-year wait for a homegrown winner at the AEGON Championships in June.

Murray is playing at the prestigious season finale for the second time following an impressive debut in Shanghai last year, when he went 3-0 in round-robin play with wins over Andy Roddick, Gilles Simon and Roger Federer before falling to Nikolay Davydenko in the semi-finals.

World No. 5 del Potro, who lost out in the round-robin stage on his debut at the season climax in 2008, clinched his place in the eight-man field in dramatic fashion – defeating Roger Federer in an epic US Open final to win his first Grand Slam title.

The 21 year old, also a title-winner at the Heineken Open (d. Querrey) in Auckland and the Legg Mason Tennis Classic in Washington, was hampered in his preparations by an abdominal injury that forced him to retire in the second round at the Shanghai ATP Masters 1000, presented by Rolex and the quarter-finals of the BNP Paribas Masters in Paris (Bercy). However, he said he is fully fit now and looking forward to the remainder of the tournament: "I feel good. I'm start to play better.  Maybe I get the confidence again to finish a good tournament here. But I have very good opponents ahead of me."