Defending champion Novak Djokovic was forced to dig deep Friday to see off Britain's Andy Murray in a thrilling five-set semi-final at the Australian Open.

In rollercoaster match lasting nearly five hours the Serbian top seed, trailing two sets to one, stormed back to win 6-3, 3-6, 6-7 (4/7), 6-1, 7-5 to set up a final with Rafael Nadal.

Djokovic, who enjoyed a stellar season in 2011, winning 10 titles including the Australian Open, Wimbledon and the US Open, drew first blood on Rod Laver Arena, breaking in the fourth game when the Scot double-faulted.

He took the opening set and broke again early in the second but Murray cut out the errors and began to dicate the points, levelling the match and taking the third set on a tie-break.

But there was a sudden momentum shift at the start of the fourth set as errors crept back into Murray's game and Djokovic raced through the gears to seal it 6-1 in just 25 minutes.

He made a crucial break in the sixth game of the final set and although Murray broke back, he won the match by breaking the Scot in the 12th game.