(Melbourne, AUS) - Top seed Novak Djokovic survived a brief injury scare before setting up an Australian Open semi-final with British rival Andy Murray on Wednesday.

The Serbian defending champion grimaced and clutched the back of his thigh during the second set against David Ferrer, and repeatedly looked tentative and uncomfortable on court.

But he shrugged off the problem to win the set on a tiebreak, and he raced through the third to see off the tenacious Spaniard 6-4, 7-6 (7/4), 6-1 in 2hr 44 min.

Djokovic, who withdrew from his 2009 Australian Open quarter-final blaming cramps and heat, and also retired in the 2007 Wimbledon semis, explained that he was simply tired after the 58-minute first set.

"I had to hang in there, especially with a player like Ferrer," he said. "I wasn't feeling very fresh after playing a long first set.... Already after a couple of games I was feeling it was going to be a long match."

The victory means Djokovic, seeking his third straight major title, now goes into a rematch of last year's title match against Murray, whom he destroyed to take his second Australian Open crown.

Djokovic put together one of the best seasons in history last year when he won 10 of 11 finals, including the Australian Open, Wimbledon and US Open, and went unbeaten for 41 matches.

But the world number one faltered at the end of 2011 with injury, and he has shown occasional vulnerability in Melbourne. In the fourth round, he was briefly troubled by veteran Lleyton Hewitt, who claimed the third set.

Earlier Murray moved smoothly into the last four with an entertaining win over Japan's Kei Nishikori, as Petra Kvitova and Maria Sharapova also reached the semis.

Despite sometimes being caught flat-footed by the flamboyant Nishikori, Murray ended the 22-year-old's historic run 6-3, 6-3, 6-1 in just 2hr 12min.

Murray is now into his fifth consecutive grand slam semi-final as he seeks the first major win by a British man in 76 years, and is on course for his third straight Melbourne title match.

After heavy defeats by Roger Federer and Djokovic in the past two finals, Murray has progressed almost unnoticed, but Ivan Lendl's new charge is unbeaten this year and has dropped just one set in reaching the last four.

Importantly Murray, whose previous opponent retired hurt, has been barely detained on court so far, leaving him physically fresh for the semi-finals.

"I'm going to have to play a lot of long points and a lot of tough points against either Ferrer or Novak, so it's good that I'm fresh," Murray said.

Four-time winner Federer and Rafael Nadal will be in action in the other semi-final on Thursday, in a rematch of the epic 2009 final which the Spaniard won in five sets.

In the women's draw, burgeoning superstar Kvitova and Russia's Sharapova set up a hotly anticipated rematch of last year's Wimbledon decider with quarter-final wins.

Kvitova, who enjoyed her breakthrough victory at Wimbledon last year, beat Italy's Sara Errani 6-4, 6-4, before Sharapova ended the fairytale run of 56th-ranked Ekaterina Makarova 6-2, 6-3.

It is the first time Sharapova has reached the final four in Melbourne since 2008, when she claimed the most recent of her three major trophies.

The Russian fourth seed has since suffered injury problems and she said her return to contention for grand slam titles vindicated her hard work in recovery and training.

"It's been a long road back to this big stage, but after hitting the winning shot you look back and think everything was worth it, no matter how tough it was," she said.

Elsewhere Australian great Margaret Court defied threats of protests over her strong views against gay marriage by visiting the tournament as a spectator.

And Sharapova said "no one important enough" had asked her to stop her infamous on-court shrieking, after the Women's Tennis Association (WTA) launched a push to tone down noisy play.