AVENTURA, Florida – Chad Johnson knew where he had to go when he struck a deal with Mayweather Promotions to box in an exhibition Sunday night.

The six-time Pro Bowl wide receiver traveled to Texas last month to train with two long-reigning champions he befriended many years ago – Jermall Charlo and Jermell Charlo. The former Cincinnati Bengal basically participated in boxing’s equivalent to two-a-days with the Charlo twins, each of whom are preparing for world title fights.

When it came time to spar with Jermell Charlo, the IBF/WBC/WBA 154-pound champion, and Jermall Charlo, the WBC middleweight champ, neither brother took it easy on the 43-year-old Johnson.

“They f--ked me up, man!,” Johnson said. “But they’ve given me a better understanding of what to expect. Even though it’s me and I wore headgear, it’s like when I got in the ring, they forgot it was me. And the people that they spar with, they forgot it was me. It was like, ‘Yo! It’s me!’ There was no white towel, nothing. I had to survive and I had to fight. They’re on a different f--king level. The first round was survivable. After that, once they turn up, I didn’t stand a f--king chance. It’s impossible.”

As poorly as it went when Johnson sparred against either Charlo, it removed fear from his mind regarding what might happen when he battles Brian Maxwell in a four-round cruiserweight exhibition at Hard Rock Stadium in Miami Gardens. The Johnson-Maxwell match will open Showtime Pay-Per-View’s four-fight event at 8 p.m. EDT ($49.99).

“It helped me big time,” Johnson said. “It also gives me a ‘I-don’t-give-a-f--k’ mentality about getting hit. Like, I don’t care.”

Johnson understandably spent more time sparring against the boxers who are helping Jermall Charlo and Jermell Charlo prepare for their respective fights against Juan Macias Montiel on June 19 and Brian Castano on July 17.

“I sparred them once apiece and then their sparring partners,” Johnson said. “And then after that, someone that was more on my level to get real work. Because you can’t get no work when you can’t hit nothing, and they can hit you at will. It’s f--king different. And then they get out the ring, and they’re back nice and smiling. I’m like, ‘Why are you smiling? You just f--ked me up!’ ”

Johnson, who weighed in at 179½ pounds Saturday, admitted he might lose to Maxwell, an uncommon confession before boxing matches.

Maxwell was stopped in the second round of his only professional boxing bout, which took place February 20 in Miami. The 33-year-old Maxwell, of Roanoke, Virginia, also is 0-3 in Bare Knuckle Fighting Championships matches and 2-3 in MMA bouts.

He has lost by technical knockout five times in a combined nine boxing, BKFC and MMA matches. Johnson, who only previously used boxing training to prepare for football seasons, remains wary of his opponent’s experience advantage.

“He’s still a fighter, with a fighting background,” Johnson said. “I don’t take that lightly.”

The jovial Johnson, who temporarily changed his name to Chad “Ochocinco” when he played for the Bengals, never thought this type of opportunity would present itself. When Mayweather and the CEO of his promotional company, Leonard Ellerbe, called to ask him to participate in this event, Johnson jumped at the opportunity.

“I’ve done everything – bull riding, played MLS soccer, you know, tried out,” Johnson said. “Why not? I’m not afraid to fail. You know? I’m not. Take chances. That’s what life is about. You know, everybody else is content. ‘Oh, why you fighting a guy with a fighting background?’ Why is everybody p-ssies these days? No disrespect. In life, sometimes it’s OK to take chances. It’s OK. This is one of those times and I’m one of the few who does that. And I don’t mind failing in front of the world.”

As nervous as he is about boxing Sunday night, he was more apprehensive about riding a bull as part of a Professional Bull Riders event in May 2011. If nothing else, Johnson’s fight with Maxwell will last a lot longer than his 1.5-second bull ride.

“I just have to protect myself because obviously he’s been training in his camp for a while,” Johnson said. “And I don’t know what to expect, so I have to react on instinct and what I’ve been taught.”

Johnson acknowledged that being in this environment has made him uncomfortable during fight week because he is out of his element.

“I’m excited, but I’m also nervous,” Johnson said. “I’m f--king nervous as sh!t, like before every kickoff. Like butterflies, the whole nine yards.”

Keith Idec is a senior writer/columnist for krikya360.com. He can be reached on Twitter @Idecboxing.