'Is that allowed': Novak Djokovic rushes off court in bizarre Australian Open drama

Novak Djokovic had his opponent and commentators scratching their heads during a bizarre stoppage in his quarter-final win at the Australian Open.

The Serbian World No.2 booked his place in the final four at Melbourne Park courtesy of a 6-4 6-3 7-6 (7-1) win against Canada's Milos Raonic on Tuesday night.

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Djokovic - looking to add to his seven Australian Open titles - was impressive against the big-serving Canadian, who hadn't dropped a single game on serve going into the contest.

In the end it was a fairly regulation win for the 16-time grand slam champion, although the match wasn't without incident.

One of the biggest talking points came during a crucial period in the third set, where both players were locked at 4-4 and Raonic was about to serve.

However, Djokovic suddenly requested time off the court so he could fix an issue with his contact lenses.

"Can you get the lenses from him please," Djokovic requested of a ballboy as viewers looked on confused.

"I didn't know this was permitted," John McEnroe said in commentary.

Raonic was visibly annoyed by the unscheduled disruption and also quizzed the chair umpire about whether Djokovic's stoppage was within the rules.

"Is that allowed?" Raonic asked.

"So I could tell you I have contacts and do it too?"

McEnroe and his fellow commentators sympathised with Raonic's concerns as Djokovic was ushered off court to deal with the issue via a medical timeout.

Officials rules state that if a player's glasses or contact lenses become compromised during a match, they are granted time to fix the issue.

After the match, Djokovic offered his apologies to the Canadian about any inconvenience it may have caused.

"I want to apologise to Milos again it's not definitely something you see often," Djokovic said immediately after the match.

"There was not a changeover moment, I apologise to the crowd it was not intentional or tactical, it was something I had to do because those few games I really could see much and I had to change my lenses."

Djokovic pays emotional tribute to ‘mentor’ Kobe Bryant

An emotional Djokovic paid tribute to NBA great Kobe Bryant after setting up a mouth-watering Australian Open semi-final with Roger Federer.

The No.2 seed will face off against Federer for the 50th time in their storied rivalry, which stands at 26 wins for Djokovic and 23 victories for the Swiss master.

Djokovic was moved to tears on court as he spoke about his fallen friend, who died with daughter Gianna and seven others in a helicopter crash in the Los Angeles hills on Sunday.

"I don't know what we could say ... it really caught us by surprise," Djokovic said.

"He was one of the greatest athletes of all time.

"He inspired myself and many other people around the world.

"I had the fortune to have a personal relationship with him and when I needed some advice and some support he was there for me.

"He was my mentor, my friend, and it's just heartbreaking to see what has happened to him and his daughter."

Big-serving Raonic hadn't lost a set on his way to the quarter-final, the fifth time he'd reached the last eight at Melbourne Park.

Djokovic broke him twice in the first two sets but the Serb began to struggle with his contact lenses in the third and took a medical time-out.

He appeared troubled for the rest of the match, but the seven-time Australian Open champion overpowered his opponent in a near-flawless tiebreak to reach the 37th grand slam semi-final of his career.

With agencies