Spanoulis made his debut with the senior men's Greek national basketball team, for the first time, in the summer of 2004, when he was selected by his then head coach at Maroussi, Greek basketball legend, Panagiotis Giannakis, to be a member of the Greek squad during the 2004 Summer Olympics, which were held in Athens, Greece. Spanoulis was able to play in front of his home country's fans at Helliniko Olympic Arena, as Greece was the Olympic Game's host country. Greece finished in 5th place in the tournament, losing to Manu Ginóbili and the eventual gold medal-winning Argentine national basketball team, 69–64, in the quarterfinals. That was tied for the 2nd highest finish for Greece, in Summer Olympics Basketball, in its history. The 5th-place finish, making Greece one of the top 5 national teams in the world, was the beginning of Greece's great run in international tournaments during the 2000s (decade).