MELBOURNE (REUTERS) - Novak Djokovic is "physically extraordinary" and can emulate Roger Federer by winning the Australian Open in his first tournament for six months, mentor Andre Agassi said on Friday (Jan 19).

The Serb, a six-time champion in Australia, arrived with question marks over his elbow injury and has played two rounds in Melbourne wearing a compression sleeve on his serving arm.

The 12-time grand slam champion has re-modelled his serving action to take the pressure off the joint but it held up during a four-set win over Gael Monfils in brutal heat on Thursday.

"If you haven't played for a long time, anything that isn't quite the centrepiece of your game, can go through a bit of a challenge," former world No. 1 Agassi, who flew in to be in Djokovic's corner, told AAP on Friday.

"With a new service motion and the pressure and the big match and not playing in a while, that was the time for it to get tested and, getting through it, he'll be a lot better for it moving forward."

Djokovic had not played a competitive match for six months before his first-round clash with American Donald Young and while that was a breeze, his battle with Monfils in 40 deg C heat proved to Agassi that the 30-year-old is battle ready.

"Recovery is not something I worry about with him," said Agassi, who added he is not working with Djokovic for "personal gain".

"Novak is physically extraordinary and he has a recovery ability that is unlike mine, probably just because the nature of how his body is made and how efficient he is.

"The guy has a capacity for pushing himself that is unique."