11. B.J. Penn vs. Sean Sherk
It was billed as the "greatest lightweight fight" in mixed martial arts history.
Former champion Sean Sherk took on the manic Hawaiian B.J. Penn, who reigned as the organization's 155-pound titleholder.
The two met at UFC 84, headlining the prolific pay-per-view event which also featured a light heavyweight showdown pitting Lyoto Machida against "The Huntington Beach Bad Boy" Tito Ortiz.
Sherk abandoned his impressive wrestling repertoire and decided to trade blows with Penn, who has long been considered to be arguably the best boxer in mixed martial arts.
"The Muscle Shark" utilized a tight boxing regimen, using a shell defense while blitz with short hooks on the inside.
Penn chipped Sherk away with the jab for three rounds, eventually rocking the Minnesota native in the waning moments of the third-round, leaving Sherk unable to continue and calling a conclusion to the prolific fight.