MELBOURNE- - Stefanos Tsitsipas found another gear when it counted to fend off Jannik Sinner in a five-set thriller and reach the Australian Open quarter-finals in a rare win for the high seeds on Sunday.
A year after dumping Sinner out of the quarters, third seed Tsitsipas crushed the Italian's hopes of a second great escape at Melbourne Park this year as he held firm to complete a 6-4 6-4 3-6 4-6 6-3 victory at a heaving Rod Laver Arena.
With the Greek dominated for two sets as Sinner roared back into the match, Tsitsipas captured the decisive break in the sixth game of the decider before sealing it in style with a cross-court forehand winner.
"I felt like I spent an eternity playing on this court," Tsitsipas said after the four-hour battle.
"What a great night. That was superb, a 'ripper', as they say here.
"I had an unbelievable opponent on the other side of the court, playing incredible tennis in the third and fourth set.
"(I) stayed really calm, just like Mr Rod Laver used to in his day," added Tsitsipas, prompting a wave from the Australian great sitting in the crowd.
The three-times Australian Open semi-finalist will meet unseeded 21-year-old Czech Jiri Lehecka for a place in the semi-finals.
Long touted as a rising star, Sinner will wonder what might have been, having had Tsitsipas on the ropes.
He had shattered one ceiling in the previous round when he secured his first Grand Slam win from two sets down against Marton Fucsovics.
But he remains winless in seven Grand Slam matches against opponents ranked in the top five.
He trudged off court slowly, shaking his head in the player's tunnel decorated with the names of champions.
"Just a couple of easy misses and the match has changed quite fast ... It was not fatigue," the downcast redhead told reporters.
"It's tough right now, for sure ... I had the momentum, I messed it up a little bit."
A misfiring cannon for the first two sets, Sinner turned the match on its head early in the third with a string of spell-binding winners.
Duping the Greek with a sumptuous drop-shot, Sinner emerged with a break and took the set with an ace down the 'T'.
No stranger to a timed bathroom break, Tsitsipas headed off court to regroup but was still rattled when he returned.
He was broken again in the third game of the fourth set when Sinner mowed down an ill-judged drop-shot.
Pushing a backhand return into the tramlines on set point, Tsitsipas's lead was erased.
For all that, the match was suddenly within the Greek's reach as Sinner double-faulted then blasted a forehand long to give up three break points in the fourth game.
Tsitsipas threw one away with a clunky backhand return, then saw the others slip through his fingers as Sinner cancelled them with raw power and an ace.
The Greek shrugged off the setback and gained another three break points as Sinner wavered again in his next service game.
The Italian saved two but buckled on the third, sending a forehand long to hand the momentum back to Tsitsipas.
The Greek reached for his most trusted weapon and locked down the match with a barrage of huge first serves.
Asked how he came through the wobble, Tsitsipas proffered a technical adjustment, saying he loosened his wrist to produce more power and accuracy on serve.
"That helped me serve it out pretty well towards the end without being too tense," he said.
"I'm happy I figured it out."