Murray specifically targeted Federer's weaker backhand side
Defending champion Andy Murray reached the final of the Qatar Open with a 6-7 (6-8) 6-2 6-2 win over Roger Federer.
The victory was Murray's fifth against the former world number one in seven ATP meetings and followed last Friday's win at a warm-up event in Abu Dhabi.
Federer claimed a tight first set after a tense tie-break, but Murray responded to comfortably take the second.
And he clinched the match in style in the decider to set up a final against American Andy Roddick on Saturday.
"It is good to have beaten him (Federer)," said Murray, the new bookmakers' favourite for the Australian Open starting on 19 January.
"He is an awesome player, arguably the greatest player of all time, so I'm happy about my performance today.
"The first set was very tight as the tie-break was bit of a back-and-forth thing for both of us. I lost that and all of a sudden there was a lot of pressure on me."
Roddick enjoyed an impressive 7-6 (7-1) 3-6 6-3 win over France's Gael Monfils - conqueror of world number one Rafael Nadal - in Friday's other semi-final.
I just couldn't give the knockout punch but it is not a big thing
Murray has the advantage from his eight previous matches against Roddick with five wins, although the Briton is a slight doubt for Saturday's final because of a back injury.
The semi-final victory maintained Murray's unbeaten start to 2009, as well as improving his impressive head-to-head record against Federer.
The 21-year-old has now beaten Federer in his last four encounters, although his opponent won the all-important US Open final last September.
Both players began the match confidently as the first set went with serve, forcing a tie-break.
Federer got the early mini-break but relinquished it with a double fault for 4-4 and it was Murray who earned the first set point, which the Swiss saved with a brilliant volley before taking the set with some punishing groundstrokes.
The world number two then had three break points in the third game of the second set but Murray produced three magnificent first serves to recover from 0-40.
And Federer's resolve began to crack as he conceded his fourth double fault to gift Murray a break for 4-2, the Scot wrapping up the set two games later courtesy of more unforced errors on the backhand from the Swiss star.
With Murray in the ascendency, the only major worry came when he required treatment on his back early in the final set, but he came out firing to break again for 3-1
And with Federer unable to mount any sort of comeback the match ended when the Swiss hammered a smash straight into the net on match point.
"It is disappointing to lose after the first set when things were going my way," said Federer.
"I just couldn't give the knockout punch but it is not a big thing. Andy is a tough player against me. I hope when big matches come, I beat him."