In his third season with Iraklis, he continued to up his numbers in the Greek League, as he averaged 6.2 points, 4.7 rebounds, 2.8 assists, 1.5 steals, and 0.4 blocks per game, during the 2001–02 Greek League season. He was selected to the Greek League's All-Star Game, for the first time that season. Diamantidis also once again played in the Pan-European secondary league, in which he averaged 7.1 points, 5.2 rebounds, 2.8 assists, 1.7 steals, and 0.8 blocks per game, during the Saporta Cup's 2001–02 season.