The 3-6 2-6 7-6 (4) 6-4 7-5 win over the world No.2 meant the young Greek superstar is into the final four at the Open for the second time in three years.
"I wasn't really thinking about a lot of things, nothing was going through my head," he told reporters in the small hours of Thursday morning.
"How would I describe myself? Nirvana. Just like, there. Playing, not thinking."
He said that minor adjustments to pace and rhythm from the third set onwards put him in with a chance to chase an unlikely victory, but it was a carefree attitude that saw him elevate his game even further.
"I just played more flawless, I really didn't care, honestly. I played with no care and that increased the level of tennis that I put out there."
The 22-year-old said that even when he was two sets down, there was no point in getting angry at himself.
"It'd be weird if I was stressed and pissed at myself after being two love down. It wouldn't make much sense."
Tsitsipas said he had no idea where this increased calmness under fire came from, but that he believed it was a mark of maturity.
"I don't know why – I woke up today and I felt really relaxed and I just felt that things were going to go my way – I don't know how to explain it," he said.
"I was very serene during the match regardless of if it was the first set or the fifth one. Maybe the absence of the crowd kept me like this, I'm not even sure. I'm trying to analyse it myself."
He likened the win to his 2019 fourth round upset of Roger Federer, where he bundled the Swiss legend out in four sets.
"It brings back really good emotions and feelings. I feel something extra, and extra connection with this court … I've had great moments, moments that have elevated me and that I'll never forget.
"It's an amazing place to play tennis."
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