Alcaraz ended the fairytale run of local Monegasque hero Valentin Vacherot with a convincing 6-4 6-4 victory on Saturday (Sunday AEST) after Sinner had looked primed to wrest the top spot from the Spaniard by the ruthless manner in which he dismantled Alexander Zverev 6-1 6-4.
The Monte Carlo Country Club duel will be the pair's first match on clay since their monumental final at the French Open last year, when Alcaraz edged the Italian in five epic sets, with many hailing it the best men's match ever played.
Since then, though, Sinner has gone on to dethrone Alcaraz in the Wimbledon final before the Spaniard got his revenge in their US Open showdown and the Italian prevailed again in their ATP Finals duel.
This will be their first meeting of 2026 after Alcaraz cemented his No.1 spot by winning the Australian Open and Sinner fell in the semi-final to Novak Djokovic -- but the Italian has since looked quite imperious as he won the Masters 1000 'sunshine double' in the US at Indian Wells and Miami.
"It doens't get much better. It's the dream match for everyone. It's going to be a really special one, the number one spot's on the line. It makes it even more special," enthused Alcaraz after ending Vacherot's latest unlikely adventure by converting three of his four break points in a tough examination.
Vacherot, who had knocked out Alex de Minaur in an exhausting quarter-final clash in front of his family and hometown friends, found the Spaniard a step too far as he succumbed in 84 minutes.
In the opening semi-final, world No.2 Sinner demonstrated the nature of the gap that he and Alcaraz have opened over the rest of the world's best as he again dominated No.3 Zverev in a fourth successive Masters 1000 semi-final meeting with the German.
The Italian became only the fourth player to reach the finals at Indian Wells, Miami and Monte Carlo in the same season, after Roger Federer, Rafael Nadal and Djokovic.
"I'm very, very happy," Sinner said. "We came here trying to give myself some feedback. Now finding myself in the final means a lot to me."
Talking about the prospect of another Alcaraz meeting before the Spaniard disposed of Vacherot, Sinner admitted: "These are matches I practice for; why I wake up. It's great to have at least one match before Roland Garros against him.
"That's for sure a big test for me. At the same time, I have nothing to lose."
