Sinner brushed past Casper Ruud 6-1 6-2 on Saturday to set up another match with Taylor Fritz - the player he beat in the US Open final two months ago and again in the group stage here on Tuesday. Both times, Sinner won in straight sets.
Earlier, Fritz beat Alexander Zverev 6-3 3-6 7-6 (7-3) as he attempts to become the first American to win the elite eight-man tournament since Pete Sampras, who defeated Andre Agassi in 1999.
Last year, Sinner lost the final to Novak Djokovic, who withdrew injured this year.
Jannik Sinner brushed Casper Ruud aside in their semi-final. (AP PHOTO)
Fritz has become the first American since 2006 to reach the title match after winning an engrossing slugfest against world No.2 Zverev.
Zverev had cruised through the group stage in majestic fashion and looked in the form to win the prestigious title for a third time, but his eight-match winning streak was ended by the resolute Fritz, who is ending the year on a high.
World No.5 Fritz had won his previous three matches against Zverev and was the better player in the opening set as the German dropped his serve for the first time this week.
Zverev hit back though to set up a deciding set and had enough chances to have taken the win, but the American dug deep to hold serve from 0-40 at 2-2 and then saved two break points at 5-5.
Fritz got ahead in the tiebreak and admirably held his nerve to match compatriot James Blake who reached the final in 2006.Â
"I felt like I played almost a perfect first set but it was tough in the second and third," said Fritz, who will end the year at a career-high world No.4 if Sinner beats Ruud.
"I found myself in some tough spots in the third, both of us really started to get on each other's serve even more. I told myself just to give him nothing from the back.
"I've been playing the top guys at the big events a lot lately. I'm getting more comfortable and confident in those moments."
16°C