ANESONGIB has branded KSI "unauthentic" after his former friend-turned-rival backed Slim Albaher to win their Misfits Boxing bout.
Gib faces Slim in Qatar on DAZN PPV on Thursday night to settle years of feuding with the American.
And in a shock twist, KSI has thrown his support to Slim despite his past friendship with Gib.
But Gib told SunSport in response: "It just seemed unauthentic. My guess is he's trying to sell the fight because everyone else is boring."
KSI, 31, and Gib, 28, share a mutual circle of friends and even began boxing at the same time in the same gym.
But their relationship strained when Gib started to take shots at KSI's Misfits promotion - which homes to celebrity-style crossover bouts.
READ MORE IN BOXING
And despite once being signed to fight Slim amid a rivalry of their own - he is in the New Yorker's corner against newfound enemy Gib.
KSI said: "I want Slim to win. I want Slim to put down Gib once and for all because this brother's been talking for the longest time.
"And now I know everyone's saying me and Gib are friends, this, this, that, that. Me and Gib aren't friends.
"We hardly ever talk, OK. So let's get this straight, we sparred, I beat him, I destroyed him, he is not on my level.
Most read in Boxing
CASINO SPECIAL - BEST CASINO WELCOME OFFERS
"So I want Slim to show the world that he is better than Gib and finally shut him up."
Already talk has turned to a grudge match between KSI and Gib down the line.
But Gib responded: "I'm taking out the best at 168 so I can't wait to do that and I'm not looking past Slim.
"We are three days away from a fight, we're solely focussed on that fight."