When the two bantamweights square off Friday in the main event of Bellator 151 from WinStar World Casino in Thackerville, Oklahoma, both know their skill sets are supreme.
For Warren (13-4), 39, an All-American wrestler at Michigan and 2006 Greco-Roman gold medalist in the FILA Wrestling World Championships, he says his experience in MMA since turning pro in 2009 has evolved his wrestling into something that can't be matched.
"Wrestling in MMA is a whole different deal than collegiate wrestling and I believe I'm the best in the world at it," Warren told ESPN.com. "I'm turning into this fighter I know I am. I have this skill set that's hard to beat."
Caldwell (8-0), a 2009 NCAA national champion at North Carolina State, disagrees about the relevance of Warren's credentials in MMA.
"I have the most respect for Joe but I just feel that he's out of his league," Caldwell said.
"The Wolf" cedes the fact that Warren, a former Bellator featherweight and bantamweight champion, may be able to get him to the ground. But Caldwell isn't concerned and believes he'll be able to get up quickly and wear out Warren's legs.
"Greco is only half of wrestling," Caldwell said. "We've seen in his fight against [Marcos] Galvao, when someone ever touches his legs, which in Greco you're not allowed to touch the legs, what happens? He cries like a little bitch."
Caldwell, 28, is looking to make a name for himself in his first main event fight with Bellator MMA. Already 5-0 in the organization with three wins via first-round submission, he said this fight is "the perfect opportunity."
"I don't think he's going to make it out of the first [round] with me," Caldwell said. "It's not Joe's time anymore, it is my time, 'The Wolf's' time. It's the young wolf versus the old wolf, and we're definitely not walking down that hill -- it's a full-out sprint."
Casual fans may best recognize Caldwell for his infamous celebration attempt last September. After defeating Shawn Bunch at Bellator 143, Caldwell did a backflip off the cage and landed on a camerawoman. The moment lives forever on social media and was ranked in SportsCenter's Not Top Ten plays of the week.
Should he be victorious Friday, Caldwell has a request for the production crew.
"I hope the camera person gives me like 30 seconds of celebration time," he said. "I should be able to get a little more face time than the two minutes we're going to be in the cage with me beating Joe up."
The self-proclaimed "Baddest Man on the Planet," Warren lost his bantamweight title to Galvao last March, but bounced back to beat L.C. Davis six months later in a performance he described as "dominating."
Warren said he had the option to wait and face the winner of last week's scheduled title rematch between Galvao and Eduardo Dantas (which was canceled days before when Galvo turned ill) but instead chose to stay active and face the unbeaten Caldwell.
With Galvao-Dantas II having been scratched for the second time, it's unclear what will happen for the winner of Friday's main event. Caldwell's suggestion that the fight should be contested for an interim belt fell on deaf ears.
Either way, Warren knew a fight with Caldwell was eventually "on the horizon" and embraced the decision to stay active.
"I fight for a living and need to take care of my family," Warren said. "I'm a fighter, so I want to fight as much as Bellator will let me."