Djokovic overcomes Ferrer to enter semi-final

Defending champion Novak Djokovic was given a thorough workout by Spain's David Ferrer on Wednesday but battled through to set up an Australian Open semi-final showdown against Andy Murray.

The tenacious Ferrer pushed Djokovic hard, manoeuvring him around the court, but the top seed stepped up his game when it mattered to win 6-4, 7-6 (7/4), 6-1 in 2hr 44min.

Djokovic earned a crucial service break in the fifth game of the first set which proved enough for him to take the lead against the fifth seed after nearly an hour full of punishing rallies.

Looking tired at the end of the first set, Djokovic produced a stunning blind, backhand winner at full stretch from the back of the court early in the second, breaking in the first game.

He looked in trouble when he grimaced in pain, clutching his left hamstring as Ferrer levelled at 2-2 but he did not appear to be restricted, going on to take the tiebreak and seize a 2-0 lead.

The Serbian stepped up a gear in the third set with Ferrer unable to keep up his earlier intensity.

"Already after a couple of games I was feeling it was going to be a long match," Djokovic said.

"There was a big mental advantage to getting two sets up," he said, adding that he had stepped up his aggression as the match wore on and it paid off.