ANDY Murray kicked off the ATP Tour Finals in emphatic style, defeating US Open champion Juan Martin Del Potro in three sets at the O2.

The Scot has enjoyed his best season to date, becoming the first Brit to reach world number two, and he made the ideal start to his last tournament of the year, eventually coming through 6-3, 3-6, 6-2.

Argentinian Del Potro has also had a season to remember, lifting his first grand slam title at Flushing Meadows in September. But Murray has always had the mental edge over the world number five and extended his head to head record to 5-1 with the win.

Having reached the semi-final stage last year, the fired-up Scot is clearly keen to end his season on a high again this year and raced to a 5-0 lead with barely 20 minutes on the clock.

The Argentine proceeded to break Murray's serve for the first time to bring the score back to 5-2, before holding his own again to return to within two games of the Scot.

But Murray was in focussed mood and needed just five points on his next game to seal the first set.

There was a sense Del Potro had found his feet at the end of the first set and so it proved at the start of the second as he punished a lax Murray to go a break up.

And the powerful Argentine continued to pile on the pressure as he served out the set.

A pumped up Murray jumped out of his seat for the start of the final set and with a fist pump and a ?come on!' The Scot clinched an early break before consolidating it to go 3-0 up.

The Argentine rallied and fought his way back into the set but he couldn't work a break point on his opponent?s serve as Murray classily progressed to a 5-2 final set lead.

And finally, the pressure proved too much for Del Potro as he threw in two double faults in the final game to suffer defeat.