Seventh-seeded de Minaur out-gunned big-serving Czech Jiri Lehecka 7-6 (7-4) 6-7 (6-8) 6-4 to power into the last eight at the Washington Open, the scene of the Australian's maiden ATP 500 final in 2018.
De Minaur's supreme returns and counter-punching yielded three breaks while he also crunched eight aces in dropping serve only twice in a tight encounter lasting two and three quarter hours.
The world No.13 could have got it done much quicker had he not double-faulted on his second match point in the second-set tiebreaker.
De Minaur then failed to serve out the match at 5-2 in the deciding set before responding with a love service hold to close out the contest.
"I dug really deep," the world No.13 said.
"I didn't want to lose having a match point in the second set and hitting a double fault.
"I told myself I was going to struggle to sleep at night, so I better do everything I can to try and win that match. It was a tough, tough match."
With his 39th ATP 500 victory since the start of 2023, de Minaur tied Alcaraz for the most wins at that level during that period.
In promising signs ahead of next month's US Open, the 26-year-old also boasts a tour-leading 19 wins on hard courts this season.
Playing his first event since suffering a deflating fourth-round loss to Novak Djokovic at Wimbledon, de Minaur next faces American Brandon Nakashima for a place in the final four.
Nakashima progressed to his 20th ATP Tour quarter-final with a 7-6 (7-3) win over Brit Cameron Norrie.
Former world No.1 and 2021 US Open champion Daniil Medvedev also advanced with a 6-3 6-2 victory over Chinese qualifier Wu Yibing.
Down to 17th in the rankings, the Russian is surprisingly chasing his first title since May of 2023.
Medvedev will play French qualifying lucky loser Corentin Moutet in the last eight.
The top half of the draw will feature an all-American semi-final between fourth seed Ben Shelton and sixth seed Frances Tiafoe and Spaniard Alejandro Davidovich taking on US world No.4 Taylor Fritz.
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