What's really driving Carwin, Mir?

Fighting. Not fighting. Talking. Not talking. Sick. Not sick. Lesnar is the most important thing to happen to the UFC since mesh-wire fencing. And for as much as this weekend's clash at the Prudential Center in Newark N.J., should be about Carwin and Mir -- both capable, dangerous fighters -- it's the pillaging Lesnar who continues to make things go.

Seared. On the brain. Lesnar is why Mir put on 25 pounds of muscle. Lesnar is the reason Carwin hasn't fought for a year.

Lesnar.

It's enough to become obsessed -- which the titleholder has accused Mir of being.

"Obviously, if I'm not victorious against Shane, then the prospects of me fighting Brock again are not happening," said the 30-year-old Mir, who split a pair of bouts with the former collegiate wrestling champion who, until his mixed martial arts venture, is best known for stardom in the world of professional wrestling.

Those fights with Lesnar, said Mir, may have prepared him better than anything else to face Carwin, an undefeated 6-foot-2, 265-pound monster whom many think is capable of matching the UFC heavyweight champion's physical force.

Mir knows nothing good can come from being on the bottom against such a specimen. Nothing good can come when hips are immobilized near the cage fencing, as his were at UFC 100 when Lesnar pummeled him to a pulp.

"If I make the same mistakes against Carwin," Mir said, "it will be a short night also."

Because of Mir's recent physical and technical enhancements, and because it's the thing fighters say, Carwin expects the former UFC heavyweight champion to be the "best Frank Mir that we've seen. That excites me."

Presuming Mir's cardio holds up under the strain of thick oxygen-demanding muscle, Carwin's analysis certainly sounds plausible.

Carwin, who can boast of never needing more than 2:11 to finish an opponent, represents the first real test of Mir's bulk-up agenda since the Las Vegan executed it with the help of World's Strongest Man veteran MarkPhilippi -- nothing less than a clear reaction to being rag-dolled by Lesnar.

"Not that I'm going to be dominant with my size, obviously but, if it can nullify Shane's strength, I think that will be the greatest indication of whether it was beneficial, without drawing away other aspects of my game," Mir said. If it works against Carwin, Mir wants to believe, it will work against his nemesis, Lesnar.

Carwin's last fight, a scare against GabrielGonzaga one year ago this month, saw him bounce back after early trouble to win by knockout when a house-sized fist crashed into the Brazilian's jaw. The victory impressed UFC officials enough for them to sign Carwin to fight for the title, and it signaled to Mir that the 35-year-old Coloradan was a fighter he'd need to eventually reckon with.

"The first time you see someone under any kind of adversity, you really get to see whether or not they're going to make it," Mir said. "I've seen more than my share of potential guys crack under the first sign of it."

No one could have known at the time that Carwin would next for Mir.

First at UFC 106 and then again at UFC 108, Carwin's title opportunities were dashed while Lesnar, battling through a painful intestinal disorder, was forced to postpone, which is why UFC officials deemed it appropriate to create Saturday's interim title fight.

Carwin was locked in. The new-and-improved Mir, 13-4, secured his spot and a No. 3 ranking by stopping CheickKongo in the first round last December.

The opportunity to fight for a UFC belt, said Carwin, ranked seventh by SI.com, represents the logical next step to an athletic career that began when he was just a kid.

Beating Mir simply means he gets what he really wanted.

"To me, the interim belt is the semifinals of getting to that championship," Carwin said. "This belt obviously isn't for the championship, and the one against Brock is. You just have to go in there and fight this fight with your heart, and hope to move onto the next round."

"I'm glad Brock's back," Carwin continued. "He's good for the sport and attracts a lot of fans. It helps the UFC explode and brings a lot of attention to the heavyweight division."

As do credible challengers, of which the Carwin-Mir winner would undoubtedly represent.