'He was there for me': Novak Djokovic breaks down in tears over Kobe Bryant tragedy

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

The Serbian superstar put on a clinical display in a quarter-final against Milos Raonic on Rod Laver Arena on Tuesday night to prevail 6-4 6-3 7-6 (7-1).

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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."

Djokovic sets up Federer showdown

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.

Earlier, Federer survived seven match points against American Tennys Sandgren to advance to a record-extending 15th Open semi-final with a heartstopping 6-3 2-6 2-6 7-6 (10-8) 6-3 win over the world No.100.

Djokovic is looking forward to renewing hostilities with his old rival.

"Obviously, I have tremendous respect for Roger and everything that he has achieved in this sport," he said.

"He has been one of the all-time greats and definitely one of my two biggest rivals.

"I have been saying this many times, I will repeat it again; the match-ups against Roger and Rafa have made me the player that I am today.

"I am grateful that I have had so many great matches against those guys."