Felix Auger-Aliassime beat Holger Rune in their only previous meeting in the Basel finalDenmark's Holger Rune reached the Paris Masters final with a two-set victory over Canada's Felix Auger-Aliassime.
The 19-year-old did not drop his serve and took five of eight break points to end in-form Auger-Aliassime's 16-match winning run with a 6-4 6-2 victory.
World number eight Auger-Aliassime, 22, won titles in Florence, Antwerp and Basel in that stretch, defeating Rune in the Swiss Indoors final last week.
But the Dane won this time to reach his first Masters 1000 final.
Rune, who beat a top-10 player for the fourth straight match including world number one Carlos Alcarez in the quarter-finals, is vying to become the first teenager to win the Paris Masters since an 18-year-old Boris Becker in 1986.
Standing in the world number 18's way will be either six-time champion Novak Djokovic or world number five Stefanos Tsitsipas, who play each other in the second semi-final.
