Pastore has been shifted from a central midfield position to the right flank and delivered two sterling performances in a 2-1 Champions League win against Porto last Tuesday and a 4-0 thrashing of Evian Thonon Gaillard in Ligue 1 on Saturday.
"He is transformed," coach Carlo Ancelotti told reporters after Pastore, who had been hugely disappointing this season after joining for a then French record 42-million euros fee from Palermo last year, created the first two goals against Evian.
"His attitude on the pitch has changed. He has worked for the team, he has defended well and his skills made the rest."
"This position in the midfield has forced me to defend more but this is what I have been training for," Pastore, whose delicate touches and inspired passes have wreaked havoc in the last two games, told reporters.
"I feel much better, more comfortable, because the team has been playing well. I feel good when the team enjoy possession and attack.
"The team's mentality has changed massively. Now, when we lose the ball, everybody makes efforts to get it back, not just one or two players."
Wednesday's game, however, will be played behind closed doors after Bastia were sanctioned following crowd incidents in the league match against neighbours AC Ajaccio earlier in the season.
A few thousand supporters are expected to gather in the stadium's car park to watch the match on a giant screen.
