By Steve Keating
Murray was in imperious form on the Canadian hardcourts, sweeping aside world number one Rafa Nadal and Federer to claim his first tournament victory of the season.
"Winning a tournament is always great, but it's the first time I beat Roger and Rafa in the same tournament, which is probably the most pleasing thing," Murray told reporters. "And I didn't drop a set against either of them.
"It's very satisfying. I mean, it doesn't happen that often for anyone.
"It's the first time I've done it ... I don't think I've ever beaten Roger in straight sets before.
"It's just good for the confidence, very satisfying, and hopefully I can keep it up."
The match began under threatening skies and just as the players finished posing for pre-match pictures, rain began to fall causing a 15-minute delay to the start.
With Federer back on court after two punishing three-set matches, including his late night semi-final over Novak Djokovic on Saturday, Murray went on the attack breaking the sluggish Swiss to open the match.
The world number four continued to pound away at a defenseless Federer, breaking him again to surge to a 3-0 lead before the 16-times grand slam winner finally hit back with a break and hold to get back into the set 3-2.
By the time Murray was serving for the first set, the Swiss master started to find his rhythm and broke the Scot a second time to level at 5-5.
But Murray appeared unfazed by the hiccup and immediately broke back before holding serve to clinch the first set.
Murray and Federer then spent more time battling the conditions than each other with rain interrupting play three times in the second set.
With skies clearing, Murray claimed the decisive break at 6-5 then clinched victory when Federer sent a return long.
Despite the loss, Federer, who will move back up to number two in the rankings on Monday, was also pleased with his play in his first event since a crushing quarter-final loss at Wimbledon.
"Today was another tough match physically with the breaks, coming back, the breaks, coming back and with all the physical strain I had to go through this week," said Federer, a two-time winner at this tournament.
"It was just kind of a touch disappointing but I thought Andy played well.
"He was aggressive. He wasn't giving me much and he clutch served at the very end when he had to and he deserved the victory."
(Editing by Pritha Sarkar/Ian Ransom)