'Worrying' Novak Djokovic admission tipped to force champion into 'super aggressive' switch

Aussie tennis great John Millman wants to see Novak Djokovic get "aggressive" if he is to make a run at an incredible 11th Australian Open title.

The 38-year-old Serbian superstar is sitting on 24 grand slam victories and has the chance to move ahead of Margaret Court's record if he wins a 25th.

But standing in his way will be the world's two best men's players, Carlos Alcaraz and Jannik Sinner, both of whom he will have to beat to lift the trophy at Melbourne Park on Sunday week.

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Those two aside, Djokovic is also battling an ageing body that even he admits is beginning to show some wear and tear.

"That, particularly in the last couple of years, is my biggest challenge. If my body holds on and the game is there, I can compete with anyone," Djokovic said at a media conference before the tournament.

"I know there are a lot of questions about whether I'm physically able to sustain the level or not. But I've been putting in a lot of work in the last couple of months to get myself to a desired level of mental and physical preparation.

"I cannot predict what's going to happen, but I can definitely assure myself and everyone else that I've given my all, as I always do in slams, particularly here in Australia."

Djokovic pulled out of the Adelaide International earlier this month in order to rest his body before the Australian Open.

He opens his campaign - his 21st, equalling the record set by Roger Federer in Melbourne - against Pedro Martinez on Rod Laver Arena on Monday night.

While there is no specific injury currently hampering the world No.4, Millman wants to see Djokovic adopt a tactic he used to beat Alex de Minaur at the grand slam three years ago.

"Novak is a wily competitor and the greatest to ever do it. I don't think you ever write off a champion, but if we are to take his words seriously, that's worrying times," Millman told Wide World of Sports' The Morning Serve.

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"He is getting a bit older and these guys (Sinner and Alcaraz) are so physical - you have to be firing on all cylinders to really compete.

"Maybe we will see Novak be really aggressive, we saw that a few years ago when he had that abdominal injury and he was super aggressive… he shortened the points and wiped Alex de Minaur off the court.

"If he is feeling it in the legs, we might see that game style and it's one that I'm really looking forward to watching. If he does, he can go really deep."

Fellow Aussie tennis great Alicia Molik believes Martinez's best chance of beating Djokovic is keeping the veteran on the court as long as possible, and making him run.

"Let's face it, Novak wants slams, that's why he's holding on, that's why he's playing, that's what he's prepping for," Alicia Molik told Stan Sport's Grand Slam Daily.

"He's meticulous with his planning, with his prep and he does absolutely everything to get himself ready, but has he played enough matches before beginning here?

"I'm not sure. I think he'll be fine. He's the player that finds his best when he's here in Australia. I mean we've seen it so many times, haven't we, over the 10 titles.

"I'd love to see him win an 11th, I think the crowds here would love that as well. I think we'd love to see him leave Melbourne at his best.

"As a tennis loving nation, and people, we have to embrace those stars that are right towards the end of their careers and really enjoy the time that we have with them. Obviously Novak is a player that's closer to that, has the end in sight, so every minute on the court is just a pleasure to watch them.

"Pedro (Martinez) would prefer this match to be a one pointer. He'd like his chances, but, look, it's going to be difficult.

"So what approach do you take? Do you want to keep Novak out on the court as long as possible? I think you'd probably be looking at a tactic like that, given he hasn't been in too many match situations."

Spanish 28-year-old Martinez is ranked No.71 in the world.