KSI has brutally layed out his issues with his brother Deji's loss to Alex Wassabi in his third boxing fight last weekend.
The British YouTube star, whose real name is JJ Olatunji, was in the front row at the OVO Arena Wembley on Saturday night to watch his brother finally square off with Wassabi after years of rivalry.
And despite coming into the fight as a huge favourite having lost almost three stone in weight, the younger Olatunji was unable to let his hands go and hardly landed a punch before losing a split decision.
Even though he lost again, the general consensus with fans and other influencers was that Deji had shown clear improvements and should continue to train, with a possible eye towards competing again in future.
But his brother disagreed, telling him in a video on his 14.8million-subscriber second channel that he was "disappointed" in the showing.
"I'm sorry if this isn't what you want to hear," KSI told his brother in a candid video. "But it's the truth, I'm not going to lie to you, I expected more from you.
"First of all, tactic-wise, how did you think you were ever going to win this fight, like what was the game plan? You're the shorter fighter with a smaller reach, so why were you slipping out of range?
"This is how I know you don't even watch boxing in general, I was watching you fight and you didn't use your brain at all, how are you going to win a fight against a taller fight on the outside?
"You stayed on the outside range and whenever you did go in, you would just ruin all your hard work by clinching and then he was out-muscling you in the clinch."
KSI has experience in this department having taken on the considerably bigger Logan Paul in his professional boxing debut, as well as a white collar bout in August 2018.
On that same night, Deji made his debut in a spirited effort against Jake Paul, which he lost in the fifth round after his corner threw in the towel.
And the elder Olatunji was highly critical of his brother's mindset, as well as his rival Wassabi's abilities, branding the American 's***', and "a joke".
"This was meant to be your easy fight," KSI continued. "And you lost.
"Now notice in the title, I didn't even say 'my thoughts on the Deji vs Alex Wassabi fight' because he's so irrelevant, so not worthy of being put in my titles.
Do you agree with KSI's criticisms of his brother Deji? Let us know your thoughts in the comments section below!
"I just don't understand, how are you going to lose your redemption fight to Alex Wassabi, man? This guy is literally a child in a grown man's body.
"Deji, where was the belief? You actually made Alex Wassabi look good - how are you going to lose weight, get fitter and then throw less punches than you did when you were fat?
"You threw less punches at 77kg than at 93kg, and I don't understand how you have some people telling you that you performed better.
"The slipping was phenomenal, but that was it, Dej, you didn't really show fitness because you didn't punch - we didn't get to see how fit you were because you threw less punches than against Vinnie Hacker."
The vicious 12-minute-long video has been viewed over 3million times in the 13 hours it's been posted to YouTube, and has garnered a mixed response on social media.
Wassabi himself has responded, mocking the Brit for taking unnecessary shots at his own brother after a loss.
"Big ups kicking your little brother when he's down," Wassabi wrote in an Instagram comment. "Class act."
But KSI replied, telling Wassabi: "Nah, I'm just letting him know that you're s*** and that he should have wiped the floor with you."
