Pospisil, No. 140 in the singles ranking, was tabbed for Friday's first singles match and the fifth match of the series, also singles, Sunday while being teamed with Daniel Nestor for Saturday's singles.
Canada is looking for just its second Davis Cup series win since the World Group format was introduced in 1981. The first came in February when the Canadian stunned perennial favorite Spain 3-2 behind a pair of win from Milos Raonic.
Raonic is still in the lineup, set for the second singles match Friday and the first one Sunday. However, much of the Canadians' hopes will lie with Pospisil, who is 4-4 in previous Davis Cup play.
He goes against world No. 18 Andreas Seppi on Friday before Raonic, 16th in the rankings, takes on No. 31 Fabio Fognini.
Pospisil and Nestor are to play the Italian team of Daniele Bracciali and Paolo Lorenzi in doubles Saturday before Sunday's reverse singles. Raonic and Seppi open the final day's play with Pospisil and Fognini set for the final match.
The Canada-Italy winner advances to the Davis Cup semifinals Sept. 13-15 against the winner of the series pitting Serbia against the United States.