Spanish top seed Rafael Nadal battled past rival Nick Kyrgios in a thrilling four-set match to reach the Australian Open quarter-finals.

Nadal, 33, had not dropped a set this tournament before 23rd seed Kyrgios provided his biggest test so far.

Kyrgios, who wore a Kobe Bryant basketball shirt in the warm-up, battled hard but Nadal came through 6-3 3-6 7-6 (8-6) 7-6 (7-4).

Nadal will face Austrian fifth seed Dominic Thiem in the last eight.

Nadal and Kyrgios have not always seen eye to eye with the rivalry blowing up last year after a tempestuous meeting in Acapulco.

Afterwards the 19-time Grand Slam champion accused Kyrgios of lacking respect before the Australian responded by calling him "super-salty".

Yet the respect for each other's ability on the court, despite their wildly contrasting styles, has rarely been in doubt and was typified by their firm handshake at the net following a riveting contest on Rod Laver Arena.

"When Nick is playing like he did today with this positive attitude he brings a lot of things to our sport," said Nadal, who won his only Australian Open title in 2009.

"I encourage him to keep working like this because he is one of the biggest talents of our tour."

Emotional Kyrgios pays tribute to Bryant

It had been billed as the latest instalment of a fiery rivalry between two players with polar opposite personalities.

But the match started in a more subdued atmosphere following the shock news of the death of American basketball great Kobe Bryant earlier on Monday.

Kyrgios is a huge basketball fan and paid tribute by wearing an LA Lakers vest bearing Bryant's name on the back as he walked out on court.

The 24-year-old Australian, who looked close to tears, kept the jersey on during the warm-up.

Bryant was a keen tennis fan and performed the coin toss before Roger Federer's US Open match against Britain's Dan Evans last year.

Nadal had also paid his own tribute earlier in the day, posting an image of Bryant on his Instagram account and telling of his "shock" at the death of "one of the world's great sportsmen".

He added: "I woke to hear this terrible news and I was super sad."

More soon.