On the verge of stepping into the UFC's octagon, an arena where some say he doesn't belong.
One of WWE's biggest stars before leaving the squared circle two years ago, Punk makes his long-awaited debut as an MMA fighter on Saturday night in UFC 203, where he won't be in the main event but where he's the top draw and greatest curiosity.
When he takes center stage a month shy of his 38th birthday, Punk, who was born Phil Brooks, will complete a two-year journey that began on Jan. 27, 2014, when he informed WWE chairman Vince McMahon that he was done with wrestling. That conversation took place in Quicken Loans Arena, where Punk's first foray in mixed martial arts will be witnessed by more than 20,000 fans and a pay-per-view audience interested in his unique story.
The symmetry is not lost on Punk, who has spent grueling hours training for his bout with 24-year-old Mickey Gall. Just as he was in his days as a brash, do-whatever-it-takes-to-win wrestler, Punk is certain he'll come out victorious.
"I belong here and my team belongs here," he said earlier this week. "I'm confident in my preparation. To me, it's never too late to start something. If you think otherwise, I'm sorry your dreams are so small."
Punk's fight with Gall will precede a heavyweight title matchup between champion - and Cleveland native - Stipe Miocic, who will take on Alistair Overeem, one of the division's top-ranked contenders. Also Fabricio Werdum, knocked out in the first round by Miocic in May, will take on Travis Browne in a rematch.
While former pro wrestler Brock Lesnar successfully transitioned from wrestling to MMA, he didn't attempt it as deep into his athletic career as Punk, who says the pace of UFC training is more conducive to family life after years on the road performing in arenas around the world.
He has spent the past 12 months in Milwaukee, working with Duke Roufus and others at the Roufusport Martial Arts Academy.
"You have good days, you have bad days. You have frustrating days. You have breakthroughs. You turn corners. You make friends. You are with your team. Your team is your family," he said. "No matter how frustrating or how bad a day got, it's still awesome I'm enjoying all of this. You've got to be a sick individual to enjoy some of the gnarlier aspects of the training, but this has been amazing."
Unlike the scripted WWE, where outcomes are decided long before wrestlers lock arms, nothing is planned inside the UFC's caged, eight-sided playpen.
Punk has prepared himself as best he can for the "chaos" that takes place, but acknowledges there are some unknowns. He's lost more than 20 pounds from his wrestling days, but feels more than adequately adept in his new sport.
"I use the correlation of you know how to drive an automatic car and now you're learning how to drive a stick shift," Punk said in comparing the athletic adjustment he's made. "If you think too much about it, you're not going to be able to do it, but if you learn and you practice and you drill and you're serious about it, you can drive it and then it becomes second nature. You're still driving a car."
For Gall, the matchup with Punk fulfills his own dream.
He gravitated to MMA after trying other sports, then took advantage of an appearance on UFC President Dana White's online series, "Looking For a Fight." Gall won his first fight, then challenged Punk immediately afterward. Without any video to watch on Punk, Gall said he's prepared for whatever comes at him.
"I'll be ready for everything," he said. "I'm going to fight my fight and I'm going to find a way to get him out of there."
Since cutting ties from wrestling to try UFC, Punk has been targeted by fans, media members and athletes who have questioned his motives and doubt his chances to succeed.
Punk doesn't care. This is no act. This is who he is now.
"It's like when Michael Jordan went from playing basketball to baseball," he said. "'Oh, baseball's too hard, he's not going to able to do it. I'm awkward, uncoordinated and I'm old and I'm fat and I'm lazy and I suck and I was a fake athlete, I'm not going to be able to do it.' If you believe all that stuff then you're not going to be able to do it."