Defending champion Novak Djokovic dismissed concerns over his fitness after outlasting David Ferrer to set up an Australian Open semi-final showdown against Andy Murray.

Djokovic caused a scare when he grimaced in pain, clutching his left hamstring at 2-2 in the second set, and looked tenatative and uncomfortable before shrugging off the problem to win the set on a tiebreak.

"Luckily for me it wasn't something that stayed there for a long time. It was just a sudden pain. But, look, you could expect before coming to this match that it's going to be very physical," said Djokovic.

The Serb gave himself a clean bill of health for Friday's semi-final against Murray, adding: "I don't have any physical issues. I feel very fit and I feel mentally, as well, very fresh."