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Vacherot, who also enjoyed a breakthrough run at the Shanghai Masters in October, knocked out Lorenzo Musetti, Hubert Hurkacz and Australia's Alex de Minaur on his way to the Monte Carlo semi-finals.

The 27-year-old was the first Monegasque player to reach the last four in the Principality.

Alcaraz struck first in the opening set, breaking serve to move 2-1 ahead before sealing the set with an ace.

Just as the seven-times grand slam champion appeared to be cruising, Vacherot mounted a spirited fightback and edged ahead 4-3 in the second set. Alcaraz, however, proved too strong, winning three successive games to seal victory.

With the win, Alcaraz became only the third player to reach 10 ATP 1000 finals before the age of 23, joining Rafa Nadal and Novak Djokovic since the format began in 1990.

With the No.1 one ranking on the line, Alcaraz said he was excited about facing Sinner for the first time this year.

"I think it's the dream spot for everyone," Alcaraz said.

"I'm fighting for my second Monte Carlo title; Jannik's fighting for his first one. It's going to be a really special one. The world number one is on the line. That makes tomorrow even more special.

"I'm just really happy to win this really difficult match against Valentin. He's playing great tennis with a lot of confidence right now. Playing in his hometown, it was really tough to deal with.

"For me, I'm really excited about my first meeting with Jannik this year, first final. Let's see how it's going to be tomorrow. I'm excited about it."