Alcaraz moved within one victory of a third consecutive Wimbledon title triumph at the age of just 22 after subduing the tough challenge of American Taylor Fritz 6-4 5-7 6-3 7-6 (8-6) on another baking hot day on Friday.
Then Sinner, at 23, ended the dream of seven-time champion Novak Djokovic in totally ruthless style, hammering the ailing Serbian great 6-3 6-3 6-4 in just under two one-sided hours to reach his first final at the All England Club.
It's set up a rematch between the game's two dominant and youthful forces following their five-and-a-half hour epic in the recent French Open final that Alcaraz won, a marathon affair so brilliant that it's been hailed as perhaps the best grand slam final ever played.
Asked what we could expect from their latest duel, Sinner could only smile: "I don't know - you saw the last final, you never know!
"It's a huge honour to share the court with Carlos. Hopefully, it's going to be a good match like the last one. I don't know if it can get better, because I don't think it's possible, but we will try to do out best and hopefully it will be an enjoyable match."
And Alcaraz was just as enthused as he declared he expected to be pushed to the limit again as he was when he saved three championship points in Paris before prevailing.
"I'm still thinking about that moment sometimes," said Alcaraz. "It was the best match that I have ever played.
"I'm not surprised he pushed me to the limit. I expect that on Sunday just to be on the limit, to be on the line. It's just going to be a great day, a great final. I'm just excited about it.
"I just hope not to be on court for five hours and a half again! But if I have to, I will."
Sinner's first final was only 18 months ago at the Australian Open, and by completing his major set at 23 in just six tournaments, he has set a new record, while the pair will also now ensure that one of them will be crowned champion at a seventh successive grand slam.
But there was huge sadness and sympathy from the crowd for 38-year-old Djokovic, who was completely outplayed and looked to be struggling, particularly in the third set, after the nasty fall he had suffered at the end of his quarter-final win over Flavio Cobolli.
Sinner applauded him off the court as the inevitable feeling arose that it could be the last time we see him the 24-time grand slam champion play at Wimbledon.
Yet Djokovic was quick to scotch that idea. "I'm not planning to finish my Wimbledon career today," he said. "I'm planning to come back definitely — at least one more time."
He wouldn't go into details about his injury, but added: "I don't want to whine about not managing to play my best. I do feel disappointed that I just wasn't able to move as well as I thought or hoped that I would."
Alcaraz, the No.2 seed, has now earned his 24th straight match victory in his best ever win streak, and there was an inevitability about how once again he managed to raise his game every time danger threatened.
Fritz had levelled the match at one set all and had the chance to take the match into a fifth-set decider when he led 6-4 in the penultimate set tiebreak, only for Alcaraz to step up again and reel off the next four points to seal victory in two hours 49 minutes.
