The 20-year-old became the youngest semi-finalist at Melbourne Park since American Andy Roddick, also 20, at the 2003 tournament.
Greek sensation Stefanos Tsitsipas added another thrilling chapter to his Australian Open odyssey on Tuesday, the 20-year-old felling Roberto Bautista Agut 7-5, 4-6, 6-4, 7-6(2) to claim a maiden Grand Slam semi-final for the Mediterranean nation.
Having already floored Roger Federer to send shockwaves through the tournament, the 14th seed can create further tennis history for his country when he plays for a spot in the final against Rafa Nadal or Frances Tiafoe.
Under a blazing sun at Rod Laver Arena, the aggressive baseliner fought back from 4-2 down in the third set and was unflappable in the final tiebreak, closing out the match with a pair of booming serves past his Spanish opponent.
With a victory that triggered a chorus of singing from Greek fans in the terraces, Tsitsipas became the youngest semi-finalist at Melbourne Park since American Andy Roddick, also 20, at the 2003 tournament.
"Feels like a fairytale almost," he said in on-court interview. "I'm living a dream, living what I worked so hard for. I feel emotional but not much.
"I told people before that Grand Slam semis was my goal. When I was answering that question I thought I was crazy. But no, it's real. It happened."
Having saved all 12 break points in his fourth round victory over double defending champion Federer, the Greek's composure was again key against Bautista Agut.
Tsitsipas was denied on a first match point at 6-5 in the fourth set but shrugged off the near-miss to dominate the tiebreak against the 22nd seed.
A backhand volley down the line put him two points from victory and he fired a serve into the corner to earn another four match points.
He only needed one of them to seal the match with another big serve, which he greeted by flopping onto the blue hardcourt, overwhelmed by the moment.
The man who conquered 20-times Grand Slam champion Federer had a rough start, however, bungling an overhead smash to be broken in the first game.
He broke back in the eighth, when Bautista Agut dealt poorly with a lob and upped the pressure at 6-5.
Blasting a run-around forehand winner to bring up two set points, he converted the second when a harried Bautista Agut found the net.
Bautista Agut remained calm, and was soon leading 3-1 in the next, having sent a backhand return whistling past Tsitsipas to break him in the second game.
The Greek was docked a serve for falling foul of the clock for a second time but responded with a second serve ace and held to 3-2.
Bautista Agut ploughed on in his unflustered way and claimed the set with a fierce serve into the corner.
A silent operator for the entire match, he permitted himself a low cry of "Come on!" on the way to his chair.
There was no let-up from the Spaniard, who wound up his big forehand and hammered at the corners, breaking Tsitsipas in the fifth game of the third set with his 29th winner.
It appeared bleak for the Greek, but Bautista Agut opened the door by dropping serve in the eighth game with a pair of unforced errors and was soon defending set points just two games later.
He saved two of them but cracked on the third, as Tsitsipas scrambled forward to retrieve a cross-court drop-shot and scooped it down the line.
Bautista Agut dug in grimly, summoning the grit that pushed him through three five-set marathons in his previous matches.
He double-faulted to give Tsitsipas a match point at 6-5 but saved it with a fearless forehand down the line and repeated the feat to send the set into a tiebreaker.
There was little he could do, however, as Tsitsipas raised his game once more, showing a composure and ruthlessness that have him marked for success at the Grand Slams as he raced away to seal victory.
