Andy Murray of Britain serves to Juan Martin Del Potro of Argentina during their ATP World Tour Finals first round tennis match in London November 22, 2009.[Xinhua/Reuters Photo]

Host favorite Andy Murray defeated reigning U.S. Open Champion Juan Martin del Potro 6-3, 3-6 and 6-2in the first single match of the ATP World Tour Finals on Sunday.

"It was a really good start," said the Scot. "Start of the match was important. Me and Juan haven't played that much since the U.S. Open. I kind of expected a little bit of a scrappy match maybe."

Murray, seeded No. 4, made a strong start by leading the first set 5-0, but the towering del Potro from Argentina won three games consecutively later to make the match unpredictable.

Although the 22-year-old Murray snatched the victory of the first set after nine games, del Potro, who overplayed world No. 1 Roger Federer in Flushing Meadow this September, revenged harshly in the second set to win 6-3.

Juan Martin Del Potro of Argentina reacts during his ATP World Tour Finals first round tennis match against Andy Murray of Britain in London November 22, 2009.[Xinhua/Reuters Photo]

In the deciding set, however, the 21-year-old del Potro surrendered quickly 2-6, losing his first match in the Group A round-robin.

"Andy played great tennis in the third set. He was a little lucky, but you need the luck to win and today (the luck) was with him," said the 5th seed.

Murray is going to play the winner between Roger Federer and Fernando Verdasco on Tuesday.