Murray is the first Briton to win a Masters title since Tim Henman in 2003
Andy Murray won his first title at the elite Masters Series level with a stunning victory over world number three Novak Djokovic in Cincinnati.
Murray repeated his defeat of the Serb at last week's Toronto Masters, beating his fellow 21-year-old 7-6 (7-4) 7-6 (7-5) in two hours and 23 minutes.
He needed six match points to seal victory after failing to serve out the match at the first attempt.
The win will see Murray ranked at a career high six in the world on Monday.
"It's huge because to win these tournaments is tough nowadays," said Murray afterwards.
"I've played five days in these conditions and had eight or nine matches in the last couple of weeks. But I've put in the physical work and it's paid off."
Djokovic enjoyed a fantastic win over world number one in waiting Rafael Nadal in the semis and went into the final with a 4-1 record against Murray.
But that solitary win for the Scot came only nine days ago and was evidence of the significant leap he has made in recent months.
It was the Briton who started the better and he cranked up the pressure in game five, forcing a break point, before earning another chance two games later.
The Serb held him off but as the set progressed it seemed a matter of when, rather than if, Murray would force the break, all the while holding his own serve with ease.
Despite not being taken past 30 on serve the Scot still required a tie-break but he remained ice cool, breaking immediately and consolidating with a huge ace.
I got very nervous and he was hitting the ball really big but I hung in well
A couple of wild Djokovic forehand errors saw Murray reach the changeover at 5-1 and he wrapped up a commanding set when the Serb sent a backhand long.
Murray finally let his level slip at 1-1 in the second set and, after two crunching forehand winners saw off the immediate danger, he went long with a backhand on the third break point to hand Djokovic the lead.
It did not last long.
The Australian Open champion double-faulted on the first point of the following game and immediately handed back the break, looking suitably disgusted with himself.
Murray stepped up a gear in game eight, moving to break point with a forehand winner and taking it when Djokovic netted a smash after some breathtaking scrambling from the Scot.
But with the title in his sights, Murray played his first edgy game of the day, throwing in two double-faults and missing four match points before Djokovic broke back.
It could have been a shattering blow for the Briton but he held on as the confidence flowed through Djokovic and managed to force a second tie-break.
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