When it was all said and done and the crowd stood up to acknowledge the legend of Federer goodbye, Tsitsipas stood on his bench staring wide-eyed at the scoreboard that read 6-7, 7-6, 7-5, 7-6.
Federer had 12 break points in a thrilling fourth-round contest in the first major of the year, but Tsitsipas saved every one and showed nerves of steel to win two tie-breaks and topple the defending champion.
"I have massive regrets". I do feel like my game is pretty good at the moment.
"I did watch a couple of his matches in the past that he played on hard courts".
"I lost to a better player who was playing very well".
"Hung in there, gave himself chances at some points, stayed calm". It's not always easy, especially for younger guys. "Credit to him for taking care of that", Federer said.
And in that 37th game it was Tsitsipas who claimed the break and with it a two sets to one lead over the champion. The Swiss has also impressed during the Hopman Cup in Perth where he won all his matches also in straight sets.
Tsitsipas was trounced by the "King of Clay" Rafael Nadal in the final, but it was not long before he provided even more compelling evidence of his rare talent. Barty pulled out of doubles on Friday with a mild strain in an effort to concentrate on singles (Barty won the U.S. Open doubles title with CoCo Vandeweghe last year).
"We all want them to win all the big stuff, but it just takes time", Federer said about the newest generation of challengers.
The NextGen Finals champion beat Federer, who is 17 years his senior, 6-7 (11-13), 7-6 (7/3), 7-5, 7-6 (7/5) on Rod Laver Arena.
Both players produced tennis of nearly mirroring playing styles, but Tsitsipas' conviction in the pressure moments proved crucial as he secured another notable victory in his burgeoning career. I think he played really well there.
The battle-hardened Spaniard progressed to the last eight following a five-set win over last year's beaten finalist, Marin Cilic.
Federer was the oldest man left in the field and would have been the oldest quarterfinalist in Australia since Ken Rosewall at 43 in 1977.
"It's a bit of a desire".