Eight-time winner Novak Djokovic faces a race to be fit for his fourth-round match at tennis' Australian Open.

The world number one was unable to train today due to an " ab muscle tear" suffered when he fell during yesterday's five-set win over Taylor Fritz.

Djokovic said he was in “huge pain” following the match, which concluded in an empty arena after the crowd was asked to leave at midnight due to a circuit break lockdown in Melbourne.

"This is definitely one of the more specials wins in my life."@DjokerNole | #AO2021 | #AusOpen pic.twitter.com/2Cx2b49RdU

— #AusOpen (@AustralianOpen) February 12, 2021

The Serb skipped practice today and instead went for an ultrasound and more treatment from his medical team.

“I will then understand what’s really going on, so that the doctor and medical team can prescribe the best possible treatment and the only way that I could even have the slightest chance to go out in less than 48 hours."

Tournament director Craig Tiley remains confident that Djokovic will get the medical green light to play through the pain.

"We'll see him. He's resilient, he's tough," he told Australian broadcaster Channel Nine.

"He'll wake up today and he'll figure out what it is and he'll go and get the appropriate treatment. The way he was, those two sets, I was pretty surprised. "But I've seen him play here, this is his court, he gets comfortable on it and he just picks his game up and up and he's that good.

"So his health is going to be important and we'll make a decision later on today on when he plays tomorrow."

The 33-year-old is set to play big-serving Canadian Milos Raonic for a place in the quarter-finals tomorrow