[2] Kantoyeu made his official debut at the 2000 Summer Olympics in Sydney, where he competed in the men's bantamweight category (54 kg).

He pinned Cuba's Wilfredo García on his opening bout, but could not beat Kyrgyzstan's Nurbin Donbaev with a score 2–5 in the prelim pool.

[3] Followed by the next morning's session, Kantoyeu delivered a striking effort to edge Kazakhstan's Maulen Mamyrov off the mat in his next match, before falling behind U.S. wrestler and 1998 world champion Sammie Henson in the semifinals without scoring a single point.

He faced against Greece's Amiran Kardanov in the bronze medal match, but nearly missed out the podium by single point behind his opponent with a score 4–5, finishing only in fourth place.

[8] He lost his opening bout to Ukrainian wrestler and 2003 world bronze medalist Oleksandr Zakharuk, but scored a single triumph to subdue Kazakhstan's Baurzhan Orazgaliyev in the prelim pool.