Francis Ngannou and Cyril Gane have offered different recollections of the champion's alleged KO of Gane during sparring.
The pair will meet in the octagon this weekend in a heavyweight title clash with Ngannou making a first defence of his belt.
Ngannou claimed this week that he knocked out his rival during a sparring session when they trained at the same Paris gym.
The pair then traded accounts of the sparring incident at the UFC 270 press conference with Ngannou recalling: "He was knocked out, probably, because he doesn’t remember."
Gane responded: "This is not the truth. We did some sparring – and it was really great sparring from Francis. It was a beautiful left kick. The problem with Francis is he doesn’t like technical sparring – (he likes) to make power.
"You gave me the left kick. You hurt me. You see? I’m honest – you hurt me. You hurt me. But you didn’t knock me down.”
Ngannou and Gane used to be training partners when the heavyweight champion worked at the 'MMA Factory' gym in France with former trainer Fernand Lopez.
However Lopez now just trains Gane with Ngannou having left the gym after a rocky working relationship with Lopez ended.
Footage was released by the gym that showed Gane winning rounds of sparring only for Ngannou to brand his former coach "evil".
He previously claimed at the media day that there were legitimate reasons why only "clips" were released from the sparring video.
First of all it wasn't the sparring footage it was a clip," Ngannou said during the UFC media day. "I knocked him out with a left high kick.
"There is a lot of reasons why the footage didn't come out, let me say this it wasn't a voluntary knockout it was in sparring it was an accident.
"I didn't intend to knock him out and I didn't go there to knock him out, so personally it isn't something I will go around and be proud of."
Who will win at UFC 270 - Francis Ngannou or Cyril Gane? Let us know in the comments section below
Ngannou has had a continually heated rivalry with Gane going into the fight due to his strained relationship with Lopez.
The 35-year-old refused to shake the rising star's hand during a backstage meeting at UFC 267 which prompted a disappointed reaction from Gane.
Sparring footage being released by the gym raised tensions further with Ngannou adamant that he knocked down his opponent later in the day.
His former trainer Lopez has moved to rubbish the claim and recalled ending the session after the accident.
“A knockdown is when a fighter is hit and he goes to the ground off his feet,” Lopez told Yahoo Sports. “A knockout is when a fighter is hit and blacks out.
"Neither of those ever happened, 100 percent no. What happened was, they were sparring and Francis threw a huge kick with his left leg that touched Ciryl.
"Ciryl got angry and said, ‘What the f*** are you doing?’ and wanted to go after him. I said, ‘Guys, let’s stop the sparring.’ Ciryl was really pissed off, but I thought it was best not to go forward, so I stopped the sparring for the day.”
