Melbourne - Austria's Dominic Thiem stunned Rafael Nadal on Wednesday to send the world number one tumbling out of the Australian Open and set up a semi-final against Alexander Zverev.
The fifth seed, beaten by Nadal in the last two French Open finals, battled past the Spaniard 7-6 (7/3), 7-6 (7/4), 4-6, 7-6 (8/6) to deny him a crack at a record-equalling 20th Grand Slam title.
He will now meet German seventh seed Zverev who shattered the dreams of veteran Stan Wawrinka 1-6, 6-3, 6-4, 6-2 to book a maiden place in a Grand Slam last four.
Awaiting the winner of that clash will be either seven-time champion Novak Djokovic or six-time winner Roger Federer, who meet in the other semi-final.
"All the match was on a very good level, I think we are both in great form," said Thiem, only the second Austrian to make the Melbourne semis after Thomas Muster - the man he sacked this week as an advisor.
"Today I had the feeling I was lucky in the right situation ... it is necessary because he is one of the greatest of all time. You need some luck to beat him."
Top seed Nadal had a 9-4 record over Thiem and had beaten him in all their five previous Slam meetings.
But the last time they played on hardcourts - at the 2018 US Open quarter-finals - it was a five-set marathon.
And the signs pointed that way again, with the opening set on serve to 2-2 before Thiem, gunning for a first Grand Slam title, worked a break point but couldn't convert.
Both baseline-huggers, it became a slugfest before Nadal managed to open some doors on the Thiem serve in game eight and he broke with a perfect lob from the back of the court.
But Thiem came roaring back, breaking back with a ripping crosscourt return. He saved a set point to take it to a tie-breaker where he stunned Nadal to seal a one set lead.
Nadal, dripping in sweat on a steamy Melbourne night, attacked in the second set and Thiem lost his serve to love to go 3-2 behind.
But the Spaniard, the 2009 champion, became riled when issued with a warning for taking too long to serve and it rattled him, sending down a double fault as Thiem squared the set at 4-4.
Nadal saved a set point and it went to another tie-break where Thiem prevailed at the crunch thanks to a lucky net cord.
The third set was similarly tight, with no breaks until Nadal teased some errors from Thiem as he served to stay in the set, pumping his fists in celebration.
But when Nadal shanked a forehand in the third game of set four to be broken the momentum swung back to the Austrian. He lost his nerve serving for the match at 5-4 before finally getting over the line in a tie-break for a famous victory.
He now faces Zverev, who bounced back after being demolished in the first set by 2014 champion Wawrinka to take control and run out a comfortable winner.
Long touted as one of the next generation capable of breaking through to end the Grand Slam dominance of Nadal, Federer and Djokovic, Zverev credited a more relaxed approach for his success in Melbourne.
"I'm doing much more things outside the court," he said, adding that after a poor performance at the recent ATP Cup he did not have high expectations.
"Maybe this is a stepping stone. Maybe this is how it should happen."
Collated results on day 10 of the Australian Open Grand Slam at Melbourne Park on Wednesday (x denotes seeding):
Alexander Zverev (GER x7) bt Stanislas Wawrinka (SUI x15) 1-6, 6-3, 6-4, 6-2
Dominic Thiem (AUT x5) bt Rafael Nadal (ESP x1) 7-6 (7/3), 7-6 (7/4), 4-6, 7-6 (8/6)
Simona Halep (ROM x4) bt Anett Kontaveit (EST x28) 6-1, 6-1
Garbine Muguruza (ESP) bt Anastasia Pavlyuchenkova (RUS x30) 7-5, 6-3