 In the 2005–06 EuroLeague season, Spanoulis made his debut in impressive fashion, earning his first All-EuroLeague Team selection as a rookie in the competition.After a stint in the NBA with the Houston Rockets during the 2006–07 season, he returned to Panathinaikos and helped lead them to a EuroLeague title in 2009, being voted the EuroLeague Final Four MVP in the process.Spanoulis' transfer to Olympiacos from Panathinaikos in the summer of 2010 marked a new step in his career, given Olympiacos' feisty rivalry with Panathinaikos.