The Australian Open has always been about the survival of the fittest but whoever comes out on top at the end of the fortnight this year will have done so after a test of the most extreme variety.

From tomorrow, forecasters are predicting temperatures will exceed 100 degrees on four consecutive days at Melbourne Park, making life highly uncomfortable for Andy Murray and Co as they try to wrest the crown from Novak Djokovic.

It is the kind of testing weather that would have most people heading indoors and cranking up the air conditioning.

Instead, Murray and the other challengers to Djokovic's title will have to win seven best-of-five-set matches in temperatures almost hot enough to fry an egg.

Many of the top players train in warm conditions in the off-season, including Murray, whose off-seasons in Miami have helped him reach the final here three times in the past four years.

But nothing really prepares players for the intense heat they can find in Melbourne, combined with the stresses of competition in the first grand slam of the year.

"When it's 40° (Celsius), it feels very different on the court," said Murray, who plays Go Soeda of Japan in the first round tomorrow.

"The court just gets so hot. The air is extremely, extremely hot as well. Here when it's 40°, it can be calm. The air feels warm in your face. Your legs and your feet burn."

As always, tournament organisers have an extreme heat policy in place, which is brought in when a combination of temperature and humidity enters a particular range.

If the policy is invoked, the roof over each of the three main courts at Melbourne Park will be closed and matches on the uncovered courts will be stopped once players have finished the set they are playing.

On-site forecasters and the chief medical officer will decide if the policy needs to be invoked, while women's matches can have a 10-minute break between the second and third sets.

But organisers believe the predicted weather will be dry heat, meaning that players are likely to have to continue competing, no matter what.

That puts an extra emphasis on fitness and endurance, something that would normally play into Murray's hands.

The Scot has worked hard in Miami to get himself in perfect shape and build strength in his back, four months after having surgery to cure a niggling, painful complaint.

Six months after his Wimbledon victory, Murray may be short of match practice but Djokovic, for one, believes he will be a contender for the title again.

"You can't really forget how to play tennis," said the Serb, who is trying to become the first man in the open era to win four straight Australian Open titles. "After a few months, I'm sure that he has made a wise decision. Sure he had a big problem with his back, had surgery.

"We practised and we played a little bit in Abu Dhabi. He's striking the ball really well. Obviously it's going to take a little bit of time to get into that matchplay mode. I'm sure that he's going to be just fine."

Having played just twice competitively since returning, Murray will not take any opponent lightly, not even 29-year-old Soeda, a Japanese player ranked 112, who has won just three grand slam matches in his career.

"He had a good 12 months about a year ago but seems to have struggled a bit in the last few months," Murray said. "But he is solid, a solid player who doesn't make too many errors and has a good backhand, so I'll need to be on it."

Thinking about the likely heat brings back memories of Ivan Lendl winning the Australian Open while sporting a French legionnaire's cap, which had a strip of cloth at the back to protect his neck.

It is two years since Lendl became Murray's coach, in which time his charge has won the Olympics, US Open and Wimbledon.

The addition of Boris Becker to Djokovic's coaching set-up is the ultimate compliment to the Murray-Lendl partnership, something the Serb readily admits.

"Andy's a main contender to win any big title wherever he plays because he has improved his game significantly since he started working with Ivan," Djokovic said.

"He's been more aggressive on the court. Grass and faster hard courts are his most preferred surfaces, I think, but in looking at the results that he has made in Melbourne Park, that makes him one of the favorites."

Murray will be pleased that his match with Soeda will be played not before 5pm local time tomorrow (6am UK time), offering him a little respite from the heat.

And as the tournament goes on, Murray knows that getting through the first week without overstretching himself is likely to be key to his hopes of going further.

"From the quarters onwards they pretty much play everything in the night," he said, continuing on the heat theme.

"But in the first week I normally play a couple early doors, and the first week's normally hotter than the second week, I've found here."

It is, of course, the same for both men and Davide Sanguinetti, Soeda's coach, knows it is going to be tough for his man.

"Actually my guy is pretty good with the heat but I think Andy will make him run a lot," the Italian said. "It's a good thing his name is Go."