Number one seed Rafael Nadal progressed to the quarter-finals of the Australian Open by seeing off Argentina's Diego Schwartzman in four sets.

Nadal, 31, won 6-3 6-7 (4-7) 6-3 6-3 on Rod Laver Arena to set up a last-eight meeting with Croatia's Marin Cilic.

Schwartzman, the 24th seed, proved Nadal's trickiest opponent so far, taking a first set of the tournament off the 16-time Grand Slam champion.

But Nadal powered through the final two sets to win in three hours, 51 minutes.

"It was a great battle. He is a good friend of mine," said Nadal

"He is a great player, in all aspects, and I feel that for a lot of moments he was serving well.

"I was able to keep fighting until the end and it is the first big match I have played in 2018. It probably helps my confidence, knowing I can resist almost four hours on court."

Sixth seed Cilic earned his place in the quarter-finals with a 6-7 (7-2) 6-3 7-6 (7-0) 7-6 (7-3) victory over Spain's 10th seed Pablo Carreno Busta.