In 2006, Spiranovic then graduated to the Australian Institute of Sport where he joined future Socceroo teammates Dario Vidošić, Bruce Djite, Nikita Rukavytsya and Nathan Burns. During his stint at the AIS, Spiranovic received a call up to a 20-man Australia U–20 national team squad for a five-match tour of South America in August 2006. Spiranovic participated in matches against Colo-Colo U–20, Universidad de Chile U–20, Chile U–20 and Argentina U–20. The South American tour was preparation for the 2006 AFC Youth Championship, the qualification campaign for the eventual 2007 FIFA U-20 World Cup.
Spiranovic joined 1. FC Nürnberg in October 2006, where he was handed the number 23 shirt. He debuted in the 2006–07 Bundesliga in a 0–0 away draw against Borussia Mönchengladbach on 30 January 2007, being substituted onto the field for Marek Nikl in the 92nd minute. Days later, Spiranovic made his full debut for 1. FC Nürnberg in a 3–0 home victory against Bayern Munich on 2 February. He was substituted off of the field for Michael Beauchamp in the 46th minute due to a corked thigh. Spiranovic briefly played for 1. FC Nürnberg U-19 in the Under 19 Bundesliga South/Southwest, he debuted in a 2–1 away defeat against Karlsruher SC U-19 on 25 February 2007. Spiranovic scored his first goal for the youth-team in a 5–3 away defeat against 1. FC Kaiserslautern U-19 on 5 April 2007. Spiranovic played his first full 90-minute game in a 1–1 home draw against Wolfsburg on 28 April. He also made two appearances in the 2006–07 DFB-Pokal, his second appearance coming in the 3–2 final victory against Stuttgart on 26 May, where Spiranovic was substituted onto the field for Marek Nikl in the 72nd minute. Winning the DFB-Pokal meant that 1. FC Nürnberg had qualified for the first-round of the 2007–08 UEFA Cup. Spiranovic completed the 2006–07 season having made 8 league appearances.
Spiranovic received a call up to a 20-man Australia U–20 national team squad for a five-match tour of South America in August 2006. Spiranovic participated in matches against Colo-Colo U–20, Universidad de Chile U–20, Chile U–20 and Argentina U–20. The South American tour was preparation for the 2006 AFC Youth Championship, the qualification campaign for the eventual 2007 FIFA U-20 World Cup. Spiranovic was selected to play at the 2006 AFC Youth Championship held in India. Australia finished in second spot of their respective group after losing to China (1–0) and defeating Thailand (3–1) and the United Arab Emirates (2–0). Australia advanced to the quarter–finals where they were defeated 2–1 against South Korea and failed to qualify for the 2007 FIFA U-20 World Cup.