Jankovic lost the first set to the Italian but roared back to post a 3-6, 6-1, 7-6 (2) victory that put her in Sunday's championship showdown with Paula Ormaechea of Argentina.
Jankovic won 14-of-19 first-services in the final set and 2-of-3 break points.
Ormaechea advanced Saturday with a 7-6 (7-5), 6-3 win over Brazilian Teliana Pereira.
Scarlett Johansson steps out with fiance after pregnancy reveal
Senate Democrats to pull all-nighter on climate change