Nadal marches on in Melbourne

World No 1 and top seed Nadal took the opener before dropping a set for the first time in the tournament as 24th seed Schwartzman levelled the contest via a second set tie-break.

However, it was the Spaniard who claimed the quarter-final place on offer, closing out the match, despite typical belligerence from his Argentine opponent, with a 6-3 6-7 6-3 6-3 victory.

Also into the last eight is world No 3 and ATP Finals winner Grigor Dimitrovwho beat home favourite Nick Kyrgios in four sets.

Dimitrov prevailed in 3hrs and 27 minutes and his 7-6 7-6 4-6 7-6 triumph means he is through to a third Melbourne quarter-final and a meeting with unseeded British No 2 Kyle Edmund.

Kyrgios had began the game hoping to become the first Australian since Mark Edmondson in 1976 to win the men's singles title but in an evenly-contested match, he faltered on the big points.

A succession of booming aces and big winners underlined the Kyrgios threat but Dimitrov was able to keep his cool at the crucial moments, claiming the first two sets via tie-breaks before his Australian opponent took the third to threaten a comeback.

Kyrgios displayed the occasional tantrum with a series of outbursts aimed at his box threatening to derail his hopes, but somehow he managed to pull himself back into the match and broke Dimitrov in the fourth when the Bulgarian was serving for the match.

However, Dimitrov, a semi-finalist last year, gathered himself and closed out the fourth set tie-break to seal his third Australian Open in the last five years.

"Playing against Nick is tricky. Two weeks ago I lost to him," said Dimitrov.

"He was serving unbelievable, competing well. He deserves a lot of praise. He fought really hard.

"Even when I was serving for the match I felt it was still not over and I could not find my spots. You have to be locked in all the time."

Nadal's victory means no matter what the outcome at the end of the second week he will remain the world No 1 after reaching the last eight in Melbourne for the 10th time.

However, he needed almost four hours to see off Schwartzman and immediately set his sights on the latter stages of the tournament.

"Now we start the second week in the quarter-finals. Now is the moment to make a step forward, to play more aggressive," said Nadal.

"It was a good test but at the same time I prefer to win in two hours than in four, but moments like this helps to be more confident in yourself, in your body."

"I know I'm going to have a tough opponent in Cilic. I need to play aggressive and play well. That's what I'm gonna try."

2014 US Open champion Cilic knows he has a tough task in seeing off Nadal, who has won five one of their previous six matches.

Cilic claimed his 100th victory in a Grand Slam match and reached his 11th quarter-final at a major, battling back from losing the first set tie-break to win a 3hr 27min contest on Margaret Court Arena courtesy of a 6-7 6-3 7-6 7-6 triumph.

"I have played great tennis from the first round against tough opponents and now I am really looking to the next match, it will definitely be a big challenge," said Cilic.

"I'm enjoying how I'm playing. Playing well. I did good in the off-season and those things are paying off on the court. It gives me good confidence, good excitement on the court, when you are winning the matches, it just pushes you a little bit more, knowing that you believe in the things that are working.

"I'm not taking for granted making the second week of a Grand Slam, I'm just trying to use the opportunities the best I can."

Australian Open - Men's Draw