Jasmine Paolini guided holders Italy to another Billie Jean King Cup final by winning a gruelling match against Ukraine's Elina Svitolina before sealing the tie in a decisive doubles encounter alongside partner Sara Errani.
World number eight Paolini came from a set down to win an exhilarating match against Svitolina 3-6 6-4 6-4 and force the deciding doubles.
French Open and Olympic champions Paolini and Errani then beat Marta Kostyuk and Lyudmyla Kichenok 6-2 6-3 to seal a 2-1 victory in the tie in Shenzhen.
Ukraine, competing in the semi-finals for the first time, had put their first point on the board when Kostyuk beat Elisabetta Cocciaretto 6-2 6-3 in the opening match.
Italy will meet Great Britain or the United States, who face each other in the semi-final on Saturday, in Sunday's showpiece.
Britain are chasing a maiden title while the US are pursuing a record-extending 19th.