Though the Russian had been almost out on his feet and struggling with cramp in the tough humid conditions in his last-16 win over Learner Tien, he again resembled the man who once made it to world No.1 as he soaked up everything the Australian No.1 could throw at him to prevail 6-4 6-4 on Friday.
It was frustration again for de Minaur as he looked to nail the 300th tour-level win of his career, carving out six break point chances only to be repelled on each occasion by the indefatigable 29-year-old 'Octopus'.
Medvedev hasn't had a great season, struggling in the slams and back down to No.18 in the rankings, but he was more like his old self as the rejuvenated figure crashed 27 winners and won most of the key energy-sapping rallies.
"I was super tired. I knew against Alex, like Learner, we were going to get a lot of long points. We had a couple in the that first set (of 29 strokes), and I knew it was going to be a long day," said Medvedev, from whom one break each set was enough.
"But I'm happy about the way I played. I was really clutch in important moments, hitting the ball great and putting him under pressure many times. I'm really happy with this level."
World No.7 de Minaur played pretty well as he eyed a second Masters final, but Medvedev, who now holds an 8-4 record against the Aussie, simply served up one of his best matches in 2025 as he targets his first tour-level title for more than two years.
That was especially true as he overcame increasing weariness during the second stanza, only to somehow dredge up a sensational game at 4-4, hitting a couple of thrilling backhand counters to get the decisive break.
For de Minaur, though, it was another story of what might have been in Masters events, even if he could at least celebrate strengthening his position as No.7 among the top-eight players on course to make the end-of-season ATP Finals in Turin.
Even more frustrating for de Minaur was that he would have have had the chance to face a lowly semi-finalist, 30-year-old Frenchman Arthur Rinderknech, sensational victor over 12th seed Felix Auger-Aliassime 6-3 6-4, in the semis.
Remarkably, world No.54 Rinderknech will join his even more unheralded cousin Valentin Vacherot in the last-four.
Monaco's world No.204 Vacherot had on Thursday shocked Danish 10th seed Holger Rune to become the second-lowest ranked player ever to reach a Masters 1000 semi-final.
The cousins' fairytale run could set up a family showdown, though Vacherot has to get past four-time Shanghai champion Novak Djokovic in his semi on Saturday.
"First of all, I follow my cousin. He's going through the emotions, and I'm trying to battle to follow and do as good as him," Rinderknech said, as Vacherot cheered him from the stands.
"It's been incredible since the beginning of the week, the whole family following from home. We are in our little world of our own...
"It's been incredible, it's been unreal. It's been a good performance from myself — happy to get the win, two sets so I can be not too tired for tomorrow."
Rinderknech also made history as the oldest first-time Masters 1000 semi-finalist since German Jan-Lennard Struff achieved the feat in Madrid in 2023.
