No. 4: Randy Couture-Tim Sylvia (UFC 68)
Photograph By Ed Mulholland/US Presswire
"The Natural" was already 43 years old when he ended a 13-month retirement to step up a weight class and fight Sylvia for the UFC heavyweight title. You could say it was vintage Couture, as the much smaller fighter floored the towering champion during the first exchange of the fight and thoroughly dominated the ensuing 25 minutes to claim UFC gold for the fifth time. Afterward, the new champ still had the energy to jump on the mike and quip: "Not bad for an old man."