These are exciting times in the UFC heavyweight division. It might be the promotion's deepest, most talented roster ever.
No one can match their size or physical strength. Being abnormally large and powerful, however, aren't the only attributes that separate them from other heavyweights.
Lesnar and Carwin also possess skill and athleticism. With so many factors in their favor, trainers throughout the mixed martial arts world must work overtime to devise fight plans that might neutralize them.
The extra work might be for naught. Outside of each other, it doesn't appear anyone will defeat Lesnar or Carwin anytime soon. There are just too many variables to overcome.
"You're looking at genetically improved athletes, and size is a factor," Carwin's manager Jason Genet told ESPN.com. "Both of those guys, Brock and Shane, if you look at their pictures in high school, in college, they were big then.
"It's just a different amount of genetic building, with two guys who are 300 pounds and can do 42-inch verticals. Their explosiveness is on the same level as guys like Georges St. Pierre, who is 180, 185 [pounds], when they are working out. How do you compete with that?"
Former heavyweight champion Frank Mir, who was overwhelmed by Lesnar during their rematch at UFC 100 in July 2009, added muscle to improve his chances against the big guys. The additional bulk didn't make a difference Saturday night.
Mir weighed in at the heavyweight limit of 265 pounds for his interim title showdown with Carwin at UFC 111 in Newark, N.J. He appeared in tiptop shape, justifying his favored status heading into the bout.
But the extra muscle would prove futile on fight night. The naturally bigger, stronger Carwin easily pushed Mir around the cage, before dropping him at 3 minutes, 48 seconds of Round 1.
"Not only are [Carwin and Lesnar] wrestlers, but very physically imposing," Carwin's strength and conditioning coach John Chambers told ESPN.com. "They have to cut down to make heavyweight. Shane starts the week off around 277 pounds; Brock starts out heavier than that, I'm sure.
"Frank Mir put on a lot of weight, but it was only recent. You can't put on a natural amount of strength, a natural amount of power very quickly, so he was sort of at a disadvantage. Though he was big, he didn't have the strength to match Shane.
"If you take a guy who is 230, 235, he's definitely going to be at a huge disadvantage because Shane is powerful, he knows how to wrestle, and his hands have gotten a lot better."
The combination of wrestling, superior size and strength would appear too much for any fighter (not named Lesnar or Carwin) to overcome. Not so, says Black House owner Ed Soares, who manages heavyweight contenders Antonio "Minotauro" Nogueira and Junior dos Santos.
Soares admits Lesnar and Carwin are solid fighters who pose difficulties for everyone, but he isn't ready to put them head and shoulders above other highly rated heavyweights.
"Anytime you're talking about a guy who weighs over 230 pounds and is wearing 4-ounce gloves, and you get in the cage, anything can happen," Soares told ESPN.com. "I don't care how much muscle you have, I don't care how much weight you have or how much stronger you get it doesn't make your chin any stronger.
"Every guy has his strategy. Brock is big and strong, he can outmuscle you. But at the end of the day, all Brock has to do is get hit on the chin and he's going to go down just like Mir did and like other people have.
"All those guys [heavyweights] have their strong points. Cain Velasquez has his strong points.
"I like what I see in what Junior has, and what he brings to the division. He might not be 265 pounds, but just being 265 pounds doesn't mean you're stronger than the guy who weighs 245 pounds. Speed kills, and there isn't anyone in the heavyweight division who is as quick and agile as Junior."
While the heavyweight spotlight shines brightest on Lesnar and Carwin at the moment, Velasquez and dos Santos will get their opportunities -- in the not-too-distant future -- to dispel the notion that size, strength and wrestling can't be overcome.
The list of contenders doesn't end with Velasquez and dos Santos. Though currently on the outside looking in, Nogueira and Mir are a handful of wins from returning to the heavyweight conversation.
In the meantime, Lesnar and Carwin will determine this summer who is the supreme heavyweight. It will be a difficult bout for each fighter, the toughest of their careers. Just don't say that to Velasquez or dos Santos.
Franklin McNeil appears regularly on ESPN.com's "MMA Live."