Roberson is of course the underdog, as he was against Le Banner, because his fight record consists of a 4-0 MMA record and a 2-1 Muay Thai record. When he was announced as Le Banner's opponent in St. Tropez last month it was assumed he was being brought in as cannon fodder. He then went on to nearly KO the French veteran, who was only saved by a partisan referee who took nearly 30 seconds to administer the ten-count.
"Monday night I got a phone call, middle of the night, a friend of mine who said he had a weird proposition for us. We talked to the French side and they were on and off but by Thursday we had an agreement in place," recalls Roberson's coach, Brian Wright of Killer B Combat Sports.
"Flight tickets came through Friday for the flight to France and on Saturday we get on the plane. We arrive at the hotel Sunday evening, weigh in on Monday afternoon and had the fight on Tuesday night. It was just insane how quick it all came together.
"It was funny because obviously they brought us in to lose but then they saw us warming up. The head of the [event's sanctioning body] came over to me and was like, ‘You guys didn't come here to lose, did you?' and we were like ‘Nope, we came here to knock Jerome out.'"
That knockout nearly came in the second round. Roberson was robbed of his first knockdown by the referee, who ruled it a slip. But even as biased a referee as this one could not declare the second knockdown moments later anything but what it was. Le Banner went down hard.
It was a dramatic moment, yet the referee suddenly adopted a leisurely air, taking an age to begin counting Le Banner as the Frenchman struggled back to perpendicularity and the waking world. The long count was followed by a preposterous charade in which the referee decided that right then was the ideal time for him to begin engaging with ringside photographers - behind him, no less - about whether they were in the right position.
"[From knockdown to restart took] 24 seconds. And then in the fourth round, Karl got kicked in the nuts and the referee called that a knockdown!" says Wright, shaking his head.
"I'm not surprised though. We knew what we were getting into, they weren't bringing us out there to win. After the fight, Jerome went on vacation with the promoter, the head of the WKN [which sanctioned the fight] and the referee for two weeks. They went to Switzerland together, in the mountains. I am not joking."
Wright says he has made an official representation of protest to the WKN regarding the officiating and result but "I am not holding my breath". He realizes there is no chance of the result being overturned and so Roberson's official kickboxing record now stands at 0-1, when it should be 1-0 with a decision win over Le Banner.
Still, the win did at least put him on the radar with GLORY matchmakers. When Pat Barry's original opponent fell through - they had been looking to match Barry with Chi Lewis-Parry, but the Brit is now fighting Brandon Vera for the ONE FC heavyweight title - Roberson's name came up. With GLORY 24 most likely being a retirement fight for Barry, there seemed a pleasing symmetry with Roberson's French adventure.
This time, at least, he gets impartial officiating and a referee who won't be spending the next fortnight sharing a chalet with his opponent. Roberson, a well-mannered if slightly intense young man of 24 years, also says he doesn't mind if GLORY matchmakers think they are bringing him in to give Barry, the hometown fighter, an edge.
"I don't really care what their intentions are in bringing me in, I know what I am going there to do. I am going in there to dominate the fight and to show my skills and what I am capable of," he says.
"I like Pat Barry, I watched him when I was younger and it is an honor for me to be able to fight him now, but I think I have the advantages here. I am faster, I have better boxing, more accuracy and more power.
"He's a good kicker, he has really powerful kicks, but I think his chin has weakened and I am going to test that. If he leaves himself open at any point, I am confident that will be the end of the fight. If he stays tight then maybe the fight can go the distance but either way I see myself winning."
Roberson's ambitions include fighting for the UFC. He wants to test himself as a fighter, whatever the ruleset or platform.
"I want to face the best of the best. That is how you find out who you really are. I want to go straight in the mix. Whoever they want to put in front of me I want to fight, whether that is GLORY or the UFC," he confirms.
"I enjoy kickboxing and MMA. They are different sports. In kickboxing I don't have to worry about the takedowns and in MMA you have the variety of techniques, you can do all different things, so I like to do both."
Wright has a background in kickboxing and Muay Thai but his gym is largely filled with MMA fighters, MMA being the larger combat sport in the US.
"Karl is the main sparring partner for [UFC light-heavyweight] Corey Anderson, he won The Ultimate Fighter [season 19] as part of Team Frankie Edgar. He and Karl are pretty much each other's primary sparring partners," he says.
"My background is in kickboxing and I have a lot of international experience in that, but we don't have any big-name kickboxing sparring partners that Karl works with. We primarily use MMA fighters for our sparring just because we have more of those around.
"Karl also wants to fight in the UFC so that is definitely somewhere we want to be in the future, depending how things go with GLORY. Karl usually fights at middleweight; his heavyweight fights have come around just because he has been taking short-notice bouts. This fight with Barry is at Denver elevation so we don't want to cut weight for that either, it suits our cardio better.
"But Karl wants that middleweight title. After this fight with Barry he is going to 187lbs and going after it, he wants to take that belt from Levin. We're looking for the big opportunities, wherever they are. Karl is a freak, at 24 years old and with so few fights he is taking on much more experienced opponents and doing well."
GLORY 24 DENVER takes place at the Magness Arena, Denver, Colorado on Friday, October 9 and airs across the US on Spike TV.