Rune, 19 and 18th in the world, will challenge former world No.1 Novak Djokovic or world No.5 Stefanos Tsitsipas in the final on Sunday.
Auger-Aliassime (8th), who was aiming for a fourth trophy in four weeks after his titles in Florence, Antwerp and Basel, saw his series of matches won consecutively stop at sixteen.
He won at the expense of the Dane in the final of the Swiss tournament last Sunday.
"I wanted to play differently from the last final (in Basel). I had to be aggressive, I think I succeeded. It was me who took control each time. The score proves it", welcomed Rune.
The young Scandinavian has a fourth consecutive final in six weeks.
So far, he has won one, in Stockholm, and lost two, in Sofia and therefore Basel.
Rune is having a dream week in the Paris arena: he has just signed four straight victories there at the expense of Top 10 players. In order, Hubert Hurkacz, Andrey Rublev, world No.1 Carlos Alcaraz - who has abandoned at the end of the second set, injured in the abdominals - and "FAA".
Saturday afternoon, Rune quickly took the upper hand over the 22-year-old Quebecer and never loosened his grip.
More enterprising, more precise, faster, particularly hard-hitting in return of service, daring at the net, he quickly took the lead 3 games to 1 never to be caught again.
Visibly blunted by the considerable amount of effort provided since mid-October, Auger-Aliassime on the contrary appeared as if in slow motion, with a time delay, approximate in its positioning, and often taken by speed.
To the point of getting no break point throughout the game.
Leaping and explosive throughout the match, Rune bagged the first set in 44 minutes, then finally escaped 4 games to 0 in the second.
He finally won in less than 1h30 min.
Ranked beyond the Top 100 at the start of 2022, the Dane will climb at least to the gates of the Top 10 on Monday.
More than a consolation prize for Auger-Aliassime, the Montrealer will settle for 6th in the world, his best ranking, and is preparing to compete for the first time in his career in the end-of-season Masters, from 13 to November 20 in Turin, Italy.
© 2022 AFP