![[WATCH] KSI Gets A Reality Check Grappling Demetrious “Mighty Mouse” Johnson](https://www.bjjee.com/wp-content/uploads/2025/06/KSI-and-Demetrious-Johnson.jpg)
YouTube star KSI recently stepped onto the mats for a grappling round against one of the greatest MMA fighters of all time — Demetrious “Mighty Mouse” Johnson.
Physically, KSI had the advantage.
Known for boxing in the cruiserweight division, he outweighed Johnson by roughly 65 to 75 pounds.
But when it comes to skill and experience in grappling, the gap couldn’t have been wider.
Johnson is a living legend, having held world titles in both the UFC and ONE Championship, and after retiring from MMA, he’s stayed active by focusing on Brazilian Jiu-Jitsu — even winning an IBJJF Master World Championship at brown belt.
KSI, on the other hand, has never competed in Jiu-Jitsu or MMA and has only fought in boxing matches.
Though he has dabbled in grappling here and there, including a past training session with Michael Bisping, that didn’t prepare him much for what happened with Johnson.
The challenge was simple for KSI: survive for one minute.
Johnson even let him start the round in Mount — but it didn’t matter.
It took just a second or two for Johnson to recover and sweep him, before submitting him with an Armbar from the top in less than 20 seconds.
Check it out on the video below:
KSI tried grappling with Demetrious Johnson and surviving for a minute, and only lasted 17 seconds 😭
🎥 @MightyMousepic.twitter.com/GGtSUgIncy
— Championship Rounds (@ChampRDS) June 16, 2025
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