What would be the top five Heavyweight Championship fights in which both fighters were undefeated going into the fight.
Ali-Frazier I Foreman-Frazier I Tyson-Spinks Holyfield-Bowe I Holmes-Cooney And, though not a championship fight, Ibeabuchi-Tua deserves a mention
Sullivan-Corbett should be considered. The only other major one prior to 1971 would be Marciano-LaStarza.