黒田博樹
Iwakuma made his first appearance on the international stage when he was named to the Japanese national team that would play in the 2004 Athens Olympics. Coming off a torrid 12–0 start to the regular season, Iwakuma took the mound in the second game of the preliminary round against the Netherlands on August 16. However, he allowed seven baserunners (three hits, three walks, and a hit-batter) and gave up three runs (two earned) against a team that was viewed as the heavy underdog, leading head coach (and acting manager) Kiyoshi Nakahata to pull him from the game after just 1 innings. Though Japan went on to win the game 8–3 behind a strong relief effort (five shutout innings) by future MLB pitcher Hiroki Kuroda, Iwakuma lost the trust of the coaching staff and did not pitch in the tournament again.