Montagna played in St Kilda's 2008 NAB Cup winning side–the club's third pre-season cup win. St Kilda defeated Richmond, and Essendon on the way to the grand final. 2008 saw Montagna continue to become vital in the St Kilda's midfield. St Kilda qualified fourth for the finals series and were defeated in the preliminary final by eventual premiers, Hawthorn. He finished the year with the most kicks in the competition and second for inside-50's. His season was rewarded by being selected for the first time to represent Australia against Ireland in the International Rules series.