MELBOURNE, Australia — With Novak Djokovic clutching his leg and struggling to breathe, it looked like the "Big 4" semifinal lineup at the Australian Open might not come together.

MELBOURNE, Australia — With Novak Djokovic clutching his leg and struggling to breathe, it looked like the "Big 4" semifinal lineup at the Australian Open might not come together.

Then Djokovic's championship instincts kicked in.

The top-ranked Serb held off No. 5 David Ferrer in a second-set tiebreaker Wednesday night and then raced through the third set for a 6-4, 7-6 (4), 6-1 win, setting up a rematch of last year's final against fourth-ranked Andy Murray.

Order was restored.

For 10 days, nearly everyone at Melbourne Park has talked about the top four players and how they are on a higher level than the rest of men's tennis. But with the other three already in the semis, Djokovic looked to be in trouble in the second set.

"No, I don't have any physical issues," Djokovic said, playing down any health concerns. "I feel very fit and I feel mentally, as well, very fresh.

"It's just today I found it very difficult after a long time to breathe because I felt the whole day my nose was closed a little bit. I just wasn't able to get enough oxygen."

The win ensured that the top four men reached the semifinals for the third time in four Grand Slams. Murray beat Kei Nishikori 6-3, 6-3, 6-1 earlier Wednesday, while second-ranked Rafael Nadal and No. 3 Roger Federer were already preparing for their semifinal showdown, their 10th clash at a major but their first meeting at that stage of a Grand Slam since 2005.

Doubts about Djokovic's temperament surfaced after he won his first major at the 2008 Australian Open. He went another 11 majors before reaching another Grand Slam final, which he lost.

In his first title defense in 2009, he struggled with breathing problems and the heat and had to retire from his quarterfinal match against Andy Roddick.

Trying again to defend the Australian Open title, and again in the quarterfinals, the 24-year-old Djokovic was leading by a set and a break when he dropped a service game against Ferrer.

At break point, he scrambled to hit a defensive lob on his backhand and didn't even wait for it to land out before turning to face the back of the court, grabbing at the back of his left leg. He leaned over and rested his head on the top of his racket. Ferrer was back in contention.

For the rest of the set, Djokovic sneaked looks at his coaches and team in the stands. He cajoled himself at the baseline and took time between points.

At times he looked exhausted. At times he looked sore.

"Look, you know, in these conditions, at this stage of the tournament, when you're playing somebody like David, somebody that has great shots from both sides from the baseline, makes you always play over five to 10 shots in the rally, your physical strength and endurance comes into question," Djokovic calmly explained of his on-court demeanor. "Actually I'm not concerned about that at all.

"I'm really fit and I have no concerns of recovering for the next match. It's just a matter of breathing better through the nose."

That may not be how Murray's new coach, Ivan Lendl, sees it. Lendl has been working with Murray this month, trying to help him break his Grand Slam title drought — the Briton has lost three major finals without winning a set, including the last two in Australia.

Lendl lost the first four Grand Slam finals he contested, before winning eight of his next 15.

He was doing some scouting Wednesday night at Rod Laver Arena, sitting about 15 rows behind the Djokovic group, surrounded by people waving Serbian flags. He couldn't have missed the sideways glances from Djokovic to his support crew, or the fact that he sat down in a line judge's chair when Ferrer challenged a line call. Murray and Djokovic have been playing each other since they were 12, and know each other so well they sometimes hit together and kick a soccer ball around.

But they haven't been on the same side of a Grand Slam draw for a while. Murray said he always seems to be drawn with Nadal, while Djokovic and Federer have frequently been on the same half.

Murray said he's not necessarily more relaxed in Australia, "just more used to being in this position because of the experience."

"Definitely have more experienced than I had at this point last year because I played deep in the Slams the last five or six of them."

To him, the prospect of not playing Nadal in the semis "doesn't make a huge difference."

"Not like the match on Friday's going to be easy, because Novak's obviously playing great tennis," he said. "It doesn't change too much."

Nadal and Federer will play on Rod Laver Arena tonight, with the Australian great in attendance — partly to celebrate 50 years since he completed his first Grand Slam of winning all four majors in 1962.

On the women's side, Victoria Azarenka reached her first Grand Slam final and staked a claim for the No. 1 ranking, beating defending champion Kim Clijsters 6-4, 1-6, 6-3 in the semifinals.

The third-seeded Azarenka recovered twice in periods when a resurgent Clijsters seemed to have the upper hand, breaking the veteran Belgian's serve three times in the third set to secure victory in only her second appearance in a major semifinal.

The 22-year-old Belarusian will play Wimbledon champion Petra Kvitova or 2008 Australian Open champion Maria Sharapova in the final Saturday night. Azarenka, Kvitova and Sharapova can all finish the tournament with the No. 1 ranking.