On September 4, 2010, after Greece's elimination in the Eighth-Finals of the 2010 FIBA World Cup, at the hands of Spain (by a score of 80–72), Diamantidis announced his immediate retirement from the senior Greek National Team. He had 16 points, 4 rebounds, 2 assists, 2 steals, and 2 blocks in his last game with Greece's national team. He finished his career bearing the Greek flag, having played in 124 games, and having scored a total of 760 points, for a scoring average of 6.13 points per game.