Iaquinta did not train with the rest of the team at the Coverciano camp early Monday and underwent a scan on a bruised knee, which he sustained during Juventus' 1-1 draw at Fiorentina at the weekend.
"Iaquinta has taken a blow to the knee joint and there is a bit of fluid," Italy team physician Andrea Ferretti was quoted as saying Monday by the ANSA news agency.
"We hope to get Iaquinta back but he must rest now. We will see if (for) one, two or three days."
Iaquinta was widely tipped to start up front for Italy with Antonio Di Natale - who scored both goals in the 2-1 victory over Ukraine last month - and Luca Toni, who has returned from a thigh injury.
The three other forwards in the Azzurri's 22-man squad are Pasquale Foggia, Cristiano Lucarelli and Fabio Quagliarella.
Midfielder Massimo Ambrosini also missed the morning session with a thigh complaint but media reports said it was not serious.
Italy captain Fabio Cannavaro is suspended for the match in Genoa. Defenders Gianluca Zambrotta and Marco Materazzi, and midfielders Mauro Camoranesi, Simone Perrotta and Alberto Aquilani are all injured.
With three games to play, Scotland leads Group B with 21 points, followed by Italy with 20 and France with 19. Georgia is sixth with seven points.
The top two nations in each group qualify for next year's tournament in Austria and Switzerland.