Djokovic battles into Aussie semi-finals

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

It was a remarkable performance from the world number one whose body language for the first two sets suggested he was suffering physically.

Indeed, it was not until the latter stages that Djokovic finally displayed some of the form which saw him dominate the rest and win three grand slam crowns in 2011.

Fifth seed Ferrer, as always, was a game opponent but lacked the weapons to trouble Djokovic, who ran out a 6-4 7-6 (7/4) 6-1 winner to advance to a clash with Murray in a repeat of last year's final he won comfortably.

When quizzed about a possible fitness issue afterwards, Djokovic was giving nothing away.

"You have to hang in there, David is a great competitor and he always makes you hit every shot," he said. "I wasn't feeling very fresh.

"It was a great match, we played for almost three hours - I think the first 30 minutes was just for the first two games.

"I was lucky to get out of the second set and that was a big mental advantage to go two sets up."

It was a result which further emphasised the gulf between the top four players and the rest as a seemingly struggling Djokovic beat the fifth best player in the world convincingly.

Although evident at the end, there seemed little between them in the early stages as Ferrer matched Djokovic stroke for stroke in some punishing baseline exchanges.

And it took a moment of brilliance from the top seed to break for 3-2 with a stunning forehand.

Despite being pushed when serving for the set he got the job done and then broke in the opening game of the second.

He may have been in command on the scoreboard but Djokovic's demeanour was not that of a man enjoying his evening's work.

Ferrer, perhaps sensing all was not well with his opponent, broke back for 2-2 and the momentum swung further in his favour when Djokovic pulled up sharply in the next game clutching his hamstring.

The top seed battled on though and even broke for a 6-5 lead only for Ferrer to hit straight back. The tie-break would prove the pivotal moment of the match.

Ferrer led 4-2 but Djokovic showed great resolve to battle back and claim the next five points and finish the set with his first fist pump of the night.

The third set was a cruise as Djokovic finally freed his shoulders and Ferrer wilted.