After the Uno fight, the UFC chose to put its lightweight title—and the division itself, in some ways—on the back burner, and “The Prodigy” chose to wander. He wandered out of the promotion, confirming his status in the division by embarrassing Takanori Gomi and Duane Ludwig, two of the best lightweights outside the UFC. He wandered out of his accustomed weight class, shocking Matt Hughes at UFC 46 to capture the welterweight title. And he wandered in both senses, as was the case when he took on a 200-plus pound Lyoto Machida at K-1 Romanex in March 2005.
In October 2006, the UFC pulled its 155-pound belt back out of mothballs and booked Sean Sherk and Kenny Florian at UFC 64 to put it back into circulation. Former welterweight standout Sherk won a fairly dominant five-round decision, and lightweight was back in business. As it happened, Penn was fresh from discovering his ceiling at 170 pounds in the form of back-to-back losses to Hughes and Georges St. Pierre, so the timing could not have been better. Penn moved back down to lightweight, avenged his loss to Pulver after coaching against him on “The Ultimate Fighter,” and was poised to challenge Sherk for the lightweight title.
Only that would have been too simple. In the first defense of his new title, a few weeks after Penn beat Pulver, Sherk defeated Hermes Franca, only to have both fighters fail their post-fight drug screenings. Just like that, the UFC lightweight title was ownerless again. This time, the promotion booked Penn against Joe Stevenson for the vacant belt. At UFC 80, Penn dominated “Joe Daddy,” leading to the indelible image of Penn being paraded around the Octagon on the shoulders of one of his cornermen, licking Stevenson’s blood off of his gloves. For those who had been waiting for the better part of a decade for Penn to assume his preordained position as the UFC's lightweight monarch, all was finally right with the world.
And so it was that Penn and Sherk met in the main event of UFC 84 on May 24, 2008. The title matchup had been an expected one, but due to that last twist of fate, it would be Penn defending against Sherk, and in the lead-up to the fight, Penn used Sherk’s PED failure to needle him at every turn. Faced with the chiseled and obsessively fit “Muscle Shark,” Penn also laughed off doubts about his conditioning—already a known question mark—saying, “I have just enough [cardio] to kick your ass, Sean!”
Penn’s assessment would turn out to be correct. The fight was a one-sided drubbing, showcasing several of the champ‘s strengths, namely: some of MMA’s best boxing of the era and some of the best takedown defense of any era. Within the first minute of the fight, Penn had effortlessly defended an earnest takedown attempt from Sherk. With that dynamic established, Penn proceeded to carve Sherk up in lopsided fashion for three rounds. Penn’s jab busted the Minnesotan’s face open as he rocked him several times, eluding the shorter man’s strikes and shucking off his sporadic and increasingly desperate takedown attempts.
In the waning seconds of the third round, Penn launched a flying knee that dropped Sherk at the base of the fence. He teed off with punches until the horn, and when a dazed Sherk was slow to move, Penn waved his hands as if to indicate the fight was over. It was part showmanship by an all-time great having an in-the-zone moment, part act of mercy towards an increasingly inert foe, and at least part pragmatism, as Penn had been showing signs of a possible hand injury. Whether referee Mario Yamasaki was already of like mind or had been swayed by Penn’s theatrics, he waved it off a second later, and the “Rude Boy from Hilo” had completed his first UFC title defense.