Murray wins Cincy as hurt Djokovic quits
Murray was already in control and leading 6-4 3-0 when Djokovic, who had received treatment to his right shoulder at the end of the first set, called it quits, raising doubts over his fitness ahead of the US Open.
It was just the second defeat this year for the in-form Djokovic, whose victories this season included the Australian Open and Wimbledon, but could not have come at a worse time with the last Grand Slam of 2011 due to start in New York on August 29.
Djokovic, chasing an unprecedented sixth Masters Series title this season, had struggled from the outset with Murray breaking his first service game.
The Serb showed some discomfort with his shoulder but was still able to break back to 3-3 and bring the crowd to life, in anticipation of a real contest.
But Murray, looking confident and efficient, broke again straight away, finishing off a magnificent rally with a superb cross-court forehand winner.
Murray served out the set and Djokovic called for a medical time-out during the interval, receiving an extensive massage to his right shoulder and upper-arm.
He returned to the court but was in clear discomfort and after dropping his first two service games to trail 3-0, he conceded defeat and came to the net to shake hands with Murray.
It was the world number four's second title in Cincinnati after he also beat Djokovic in the 2008 final and his seventh overall Masters crown and a major boost to his preparations for Flushing Meadows.
Murray knows that Cincinnati is a far cry from a Grand Slam but he was encouraged by the fact he performed so well on a surface and in weather that is comparable to what awaits at the US Open.
"I think the conditions are similar. It's normally pretty humid in New York and the courts are very similar to the ones here," said the Scotsman.
"So if you can get a few matches here and play well, it gives you good confidence going into the US Open. It's not a huge change in surface or speed of court, so that definitely helps."
If Djokovic is the man to beat in New York, Murray at least has the confidence of having beaten him four times, all of them on hard courts, including twice in Cincinnati and he said conditions had been a factor in his wins.
"I would say that the conditions have probably played quite a big part in it," Murray said.
"When I played him in the heat in the Miami final I played well, here when I played him in the final it was very hot, and then today again it was very hot until the clouds came over at the end of the first set."
The Serb's retirement did take the shine off Murray's victory but he was clearly buoyed by a week of improved tennis.
"I would have obviously liked to have won by finishing the match but it happens sometimes," Murray said.
"I have to look at the week as a whole. It's been a very good week. Coming in here I had played badly in Montreal, so I needed to have a good week.
"Regardless of the match today, I was happy with the way that it had gone. Glad I managed to win today, but unfortunate the way it happened."