Though the matchup is a sure bet to draw a strong contingent of MMA and pro wrestling fans alike, Mir, who coaches a team of eight prospects on "The Ultimate Fighter 8" show, believes inexperience will prove to be Lesnar's greatest inhibitor at UFC 91.
"I think it's too early in his career," says Mir of Lesnar, who will be 14 years Couture's junior when they meet in the Octagon. "I think he's a great wrestler, powerful background, but Randy Couture is one of the most decorated Greco-Roman wrestlers we've ever had in our country. He has 12 years of MMA experience and he has the same background as Lesnar. Lesnar is basically the new Randy, a better athlete, bigger and more powerful and more dangerous, but he only has two years of [MMA] experience."
Comparing college wrestling credentials, Lesnar might be considered to have a slight edge. The University of Minnesota alumnus was the 2000 NCAA heavyweight champion, a runner-up the year before, and a two-time Big 10 champion en route to becoming a two-time All American (Lesnar joined the university as a junior).
Couture peaked as an NCAA runner-up in his junior and senior years, though he was also a three-time All-American and a member of two Division I national championship-winning teams for storied Oklahoma State.
The roads diverge substantially beyond college wrestling, though, which is where Mir sees the biggest chasm between the two.
While Lesnar, 31, graduated and pursued short-lived careers in pro wrestling and even the NFL, Couture was an eight-time world team member who placed in over 30 international tournaments around the globe beginning in 1983.
From 1988-2000, sometimes between UFC appearances, Couture weathered stringent elimination trials to become an alternate for four U.S. Olympic squads, missing the chance to compete for his country by one or two slots each time.
At the age of 33, Couture entered his first fight on two weeks' notice. Eleven years later, Couture (16-8) has become a UFC champion six times over.
The 45-year-old legend will be Lesnar's fourth MMA opponent since the former WWE champion crossed over into the sport two years ago.
Mir's assertion is not based just on the numbers. A former UFC heavyweight champion himself, Mir was one of those three men to experience Lesnar's potential, in a February 2008 contest.
Although Mir (11-3) can vividly describe the pain that follows a high-impact punch or knee, his bout with Lesnar had a different feeling altogether.
"He was more like getting hit by a car that's moving very slowly and you can't get out of the way," says Mir. "It bumps and knocks you over and is just overwhelmingly powerful."
Clinging to the underside of Lesnar's hulking, 6-foot-3, 280-pound frame, Mir hadn't realized he had gone for two arm bars in the scuffle before transitioning to the fight-ending knee bar until he watched the tape later.
"I didn't know where he was half the time," he says. "It really felt like I was underwater and somebody was beating the s--- out of me. I was just drowning under him."
In the six months that passed between Mir's victory and Lesnar's last altercation with Heath Herring (28-14) at UFC 87, the Las Vegas native says he's seen little improvement in the wrestling convert's ability to finish a fight.
Lesnar knocked Herring down surprisingly with a scorching right in the bout's opening seconds, but reverted to holding and out-positioning the Texan to earn a three-round unanimous decision.
"There was times where you could look and be like, 'Wow, man, if this guy had had two months of jiu-jitsu, he could have gone just like this,'" Mir says while mimicking a choke, "and this fight would have been over with."
Mir, 29, has good reason to keep tabs on Lesnar's progress. A rematch is on the periphery if Mir sails past fellow Brazilian jiu-jitsu black belt and UFC interim heavyweight champion Antonio Rodrigo Nogueira in December. To the victor will go the spoils of a unification match against the Couture-Lesnar winner in 2009.
That Lesnar, a novice who has fought one-fifth the amount of bouts Mir has, gets in on the championship action doesn't bother Mir in the least.
"I can get why Brock Lesnar's getting the fight," he says. "It's not like I think it absurd. If Brock Lesnar was fighting some bum off the street, it would be a main event card. That's Brock Lesnar. If Kimbo Slice came into the UFC tomorrow, he's probably going to be above me. That's just the way it is. It's name recognition."
In Lesnar, who has demonstrated a strong work ethic since joining the Minnesota Martial Arts Academy for his training, Mir sees a respected peer, albeit one who needs more time to develop his skills in the cage.
"A guy like Brock Lesnar doesn't upset me at all," says Mir. "I think he has the potential to be a very legitimate martial artist. So when I stretched out his leg and felt him tapping, I didn't even try to extend it even further. But somebody like a Kimbo or somebody like that who I don't think respects the sport, like a 'Krazy Horse,' I don't think they have a place in it. The referee couldn't get to me fast enough."
Loretta Hunt is a contributor to Sherdog.com.