K-1 World MAX 2005 Champions Challenge was held in Tokyo at the Yoyogi National Gymnasium, on Wednesday, October 12, 2005. It was a one match showcase event, featuring twenty-six fighters, representing nine countries in total. Eleven of the matches were fought under K-1 MAX Rules (70 kg/152 lb weight class), while two of the matches were fought under K-1 MMA Rules. The main event featured reigning K-1 MAX 2005 world champion Andy Souwer against Japanese fighter Kozo Takeda.