Italy coach Cesare Prandelli is being tipped to field Juventus forward Sebastian Giovinco and AS Roma\'s Pablo Osvaldo up front when his side start their World Cup qualifying campaign against Bulgaria in Sofia on Friday. Prandelli has to make changes in attack because he is without Manchester City\'s Mario Balotelli and Inter Milan\'s Antonio Cassano, the forwards he used most during the Azzurri\'s run to the final of Euro 2012. Balotelli is unavailable after having surgery on an eye problem and Cassano is not 100% fully match fit, although he did score in Inter\'s 3-1 defeat to Roma on Sunday before coming off early in the second half. Giovinco, who was part of Prandelli\'s Euro 2012 but hardly featured, scored twice in Juve\'s 4-1 drubbing of Udinese on Sunday to help maintain the Turin side\'s perfect start to the season. Argentine-born Osvaldo, who played twice for the Azzurri last season but failed to make the Euro 2012 squad, has also netted twice so far this term, including a delightful chipped effort in Roma\'s 3-1 victory over Inter last weekend. Defenders Federico Balzaretti and Davide Astori had to pull out of the squad on Tuesday with leg injuries, forcing Prandelli to call up Milan\'s uncapped centre back Francesco Acerbi. Roma midfielder Daniele De Rossi, however, is expected to be fit enough to play following a mild ankle sprain. The Azzurri face Malta in Modena on Tuesday in their second World Cup qualifier.