Novak Djokovic’s long-awaited return to Melbourne Park could very well be over before it’s even begun.

The nine-time Australian Open winner exited his Wednesday afternoon practice match against Daniil Medvedev early after seeking treatment on his left leg.

The session was meant to last for 75 minutes, but Djokovic bowed out after just 36 minutes.

Djokovic broke the Russian former world No.1 in the opening game but, when leading 3-2, received treatment, with a member of his team completing some knee extensions.

Knee extensions can be used to release the hamstring.

NCA Newswire reports that doctors assessed his knee at three consecutive changes of end and the star wasn’t “moving very well”.

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Djokovic pushed through hamstring tightness to claim last week’s Adelaide International 1 and was a firm favourite for a 10th Melbourne Park title.

He tweaked his left hamstring in the semi-final in South Australia when also playing Medvedev and required a medical time-out, but recovered to win that game, then the final.

Djokovic had reassured onlookers about his form in a post-match interview.

Wednesday’s practice match with Medvedev at Rod Laver Arena was the first time Djokovic had played in front of the Melbourne public since last year’s deportation saga.

Spanish veteran Pablo Andújar took Djokovic’s place as Medvedev remained on court.

The injury scare casts doubt over Djokovic’s ability to play in another exhibition match against Aussie Nick Kyrgios on Friday night.

The highly-anticipated contest is due to take place on Centre Court at Rod Laver Arena, with tickets having sold out in just 58 minutes.

-with AAP