Briton Andy Murray overcame sweltering heat to beat Argentine Juan Martin Del Porto 6-7 7-6 6-1 in the Montreal Masters final last night.

A day after replacing Rafael Nadal as world number two, Murray delivered a gritty performance to wear down the towering Argentine in two hours, 42 minutes under a broiling sun.

It was Murray's fifth win of the season and he becomes the first Britain in 128 years to lift the Canadian title.

The victory completed a perfect start to the North American hardcourt season for the 22-year-old Scotsman, who was returning to action for the first time since his semi-final loss to Andy Roddick at Wimbledon.

Del Potro, coming off victory in Washington the previous week and riding a 10-match winning streak, took a tight opening set in a tiebreak 7-4.

But Murray, who spent two weeks in Florida training for the severe conditions he faced in Montreal, did not buckle under Del Potro's thundering groundstrokes, getting back on level terms after clinching the second set with a 7-3 tiebreak.

The sixth-seeded Argentine player had nothing left to give in the third set as Murray moved in for the kill on his wilting opponent, recording two early breaks to go 4-0 up before finishing the match with an emphatic ace.