Greece’s Tsitsipas looked down and out after losing the first two sets but after edging the third he was a different player, taking the upper hand over a subdued Nadal to win 3-6, 2-6, 7-6 (7/4), 6-4, 7-5.
Tsitsipas, 22, stunned Roger Federer in the 2019 last 16 before being halted by Nadal in the semis, but he turned the tables to set up a last-four meeting with Russia’s Daniil Medvedev.
Underlining the scale of the upset, it was only the second time Nadal has lost a Grand Slam five-setter from two sets to love after his defeat to Fabio Fognini at the 2015 US Open.
“I don’t know what happened after the third set — I flew like a little bird, everything was working for me,” the fifth seed said.
“The emotions at the end were indescribable, they were something else.”
The defeat will sting for Nadal, who was drawing closer to a 21st major title and sole ownership of the all-time men’s record he currently shares with the injury-sidelined Federer.
Tsitsipas’s reward is a meeting on Friday with Medvedev, his third Grand Slam semi, with top-ranked Novak Djokovic or Russian qualifier Aslan Karatsev waiting in Sunday’s final.
Meanwhile, fans will no longer be able to see Barty, the world number one whose dreams of ending Australia’s 43-year wait for a domestic winner were dashed by the unlikely figure of Karolina Muchova.
Stefanos Tsitsipas ended Rafael Nadal’s Grand Slam record bid in five gripping sets on Wednesday as home hopes were dashed when top-ranked Ashleigh Barty was knocked out in the Australian Open quarterfinals.
In hot conditions, Barty raced through the first set but Muchova dominated after a medical timeout for dizziness, winning 1-6, 6-3, 6-2 to reach her first Grand Slam semi-final as the Australian crumbled.
“I was a bit lost on the court and my head was spinning so I took a break,” said Muchova, while Barty, a semi-finalist last year, called her latest near-miss “heartbreaking”.