The Australian Open has a dream men's semi-final line-up, but reigning champion Novak Djokovic will carry some physical queries into the tournament's final stages.
The world number one's 6-4, 7-6 (7-4), 6-1 quarter-final victory over dogged Spanish fifth seed David Ferrer on Wednesday night ensured the 'Big Four' became the last four at Melbourne Park for the first time.
The Serbian star set up a semi-final rematch of last year's final against Scot Andy Murray.
But Djokovic will enter that clash with some concerns, after clutching at his left hamstring at one point against Ferrer and appearing to struggle with his breathing for long stages.
Earlier, Murray blitzed Japan's Kei Nishikori 6-3, 6-3, 6-1 to book his own berth in Friday night's semi-final.
Second seed Rafael Nadal and third seed Roger Federer were already set to renew their long-time rivalry in the other semi-final, on Thursday night.
While Djokovic did not call for a medical time-out or a trainer against Ferrer, the match changed complexion early in the second set.
Djokovic was up a set and a break and in control.
But he limped to the change of ends after the third game of the set, then pulled up sharply stretching for a shot as he gave up his serve in the fourth game, clutching at his hamstring, then grimacing and squatting in pain.
At other stages, he appeared to complain about breathing problems.
Djokovic played down his physical problems, but says winning the second set had been vital.
"It was a big mental advantage," he said.
"The momentum was on my side. I managed to step it up and was very aggressive and it paid off."
Even in the first set, it had been a tough fight against short-statured running machine Ferrer, whose willingness and ability to chase down ball after ball made for some long rallies.
But once Djokovic's physical condition dipped in the second set, the 29-year-old Spaniard's hopes of making his second consecutive Australian Open semi-final grew.
Despite going down a second break of serve, he broke back when Djokovic was serving for the second set, then led early in the tie-breaker.
But Ferrer made some crucial errors late in the tiebreaker to hand Djokovic the set.
Djokovic charged to a straight sets win.
Murray will take a 10-match winning streak into their semi-final, having won the Brisbane International before his Melbourne Park run.
But Djokovic can call on the memory of blitzing fellow 24-year-old Murray on the same court in last year's final.
Still, Djokovic says Murray is an improved player from the one he beat in last year's final.
"I'm going to try to repeat the same game like last year, I guess, but I'm going to need more than that," he said.
"Andy is in great shape, he has (new coach) Ivan Lendl on his side.
"You can feel that he's physically fit and eager to win his first grand slam."
AAPTags: tennis, sport, melbourne-3000 First posted January 25, 2012 22:32:55