Rafael Nadal has survived his sternest test yet at the Australian Open to safely progress to the quarter-finals at Melbourne Park.

The world No.1 dropped serve – and his nerve – for the first time all campaign before battling past Kei Nishikori 7-6 (7-3) 7-5 7-6 (7-3) in three hours and 17 minutes.

Nadal exchanged angry words with Greek chair umpire Evanthia Asderaki after being hit with a time violation serving at 4-all and deuce in the third set.

The rattled top seed lost the next two points to hand Nishikori the chance to serve out the set, but Japan’s 16th seed failed to capitalise on Nadal’s rare lapse as the Spaniard rallied to clinch victory after another tiebreaker.

In a rough day at the office, Nadal also needed running repairs for hand blisters and a broken shoelace.

He was broken in the fourth game of the match, ending his run of 30 straight service holds, before fighting back to take the opening set in a tiebreaker.

Nishikori broke him again to build a 4-2 lead in the second set before the Spanish bull rallied once more to take a stranglehold on the match.

The 2009 Open champion and runner-up to Novak Djokiovic in his most recent appearance in 2012, Nadal dropped serve for a third and fourth time in the third set but still found a way to book his spot in a 26th grand slam quarter-final – and seventh from nine starts in Melbourne.

The hard-earned victory – after three routine straight-sets wins – set up a showdown on Wednesday with rising Bulgarian Grigor Dimitrov, the 22-year-old 22nd seed who many rate as a future world No.1.

Dimitrov earlier on Monday defeated Argentinian Roberto Bautista Agut 6-3 3-6 6-2 6-4 to qualify for his first-ever grand slam quarter-final.

Coached by Lleyton Hewitt’s former mentor Roger Rasheed, the 22-year-old recovered from 0-30 down at 4-4 in the fourth set to hold serve and set up a chance to win the match.

He took that chance with combative stroke play, breaking Bautista Agut to close out a four-set victory.

Dimitrov’s serve was a major asset, slamming 11 aces with his fastest at 219km/hr.

An elated Dimitrov was all smiles at making the last eight at Melbourne Park.

“I feel great, a bit tired, he gave me hell out here today,” he said.

“But I’m just happy.”

Best known as the boyfriend to Russian world No.3 Maria Sharapova, Dimitrov will play the winner between world No.1 Rafael Nadal and Japanese 16th seed Kei Nishikori in the quarter-finals.