Lorenzo Sonego battled past Denis Shapovalov in three sets to give Italy a 1-0 advantage over Canada in their Davis Cup semi-final on Saturday.
World number 45 Sonego sealed a 7-6 (7/4), 6-7 (5/7), 6-4 victory in 3hr 14min after back-to-back double faults from 18th-ranked Shapovalov, who had won their only previous meeting in Rome earlier this year.
Canada will look to keep their bid to reach Sunday's final alive with world number six Felix Auger-Aliassime taking on Italy's Lorenzo Musetti in the second singles tie.
Shapovalov will then come back on court to join teammate Vasek Pospisil in the doubles against Italy's Simone Bolelli and Fabio Fognini.
The eventual winners will face 28-times champions Australia who reached their first Davis Cup final since 2003 on Friday with a 2-1 win over last year's runners-up Croatia.
Italy have reached the finals seven times, winning the trophy in 1976.
Canada have never triumphed in the team event, losing their only previous final in 2019 to Spain.
Eliminated in the qualifying rounds, the Canadians were handed a wild card.
The invitation to the finals had been originally destined for Serbia, but became vacant when Novak Djokovic's side replaced Russia, the holders expelled over the invasion of Ukraine.