World number one Sinner fought back from a set down in front of a packed centre court to continue his march towards a first Foro Italico title.
After a strangely slow start, Sinner again showed good form on centre court, where, since returning to action last week from a three-month doping ban, he has taken his unbeaten run to 26 matches.
And the 23-year-old will face down Alcaraz, the last man to beat Sinner in the final at the China Open in early October, with all eyes on another potential final between the pair at Roland Garros next month.
A win for Sinner against his rival would give the men’s Rome title to an Italian for the first time since Adriano Panatta in 1976.
Alcaraz booked his place in the final earlier on Friday by beating Sinner’s countryman Lorenzo Musetti 6-3, 7-6 (7/4).
The four-time Grand Slam champion overcame Musetti and the windy conditions in just over two hours to reach his fourth final of the season. (AFP)
