Superstar Youtuber and occasional celebrity boxer KSI recently challenged MMA legend Demetrious ‘Mighty Mouse’ Johnson to a grappling match, and quickly found himself being tied up in knots by the former UFC and ONE FC champion.

The challenge was simple enough – the 6ft, 210lb KSI just had to survive for 60 seconds on the mat with the 5ft 3″, 145lb Johnson, and to make things easier he even got to start on top of him in full mount.

However, it quickly became apparent that this was going to be way harder than KSI expected, with Johnson easily escaping from underneath him and catching him in a submission in less than 20 seconds.

And despite getting multiple other opportunities to repeat the challenge, KSI continued to be stunned by just easily ‘Mighty Mouse’ was able to manhandle him and force frequent tapouts.

Of course all of this is no surprise to seasoned MMA fans given that Johnson is widely considered one of the greatest MMA fighters of all-time, and successfully defended his UFC flyweight title 11 times, before going on to win the ONE FC flyweight title.

The 38-year-old Johnson is now retired, but he still successfully competes in grappling tournaments for fun.

Check out highlights of their session below or scroll down to watch the full video from Johnson’s channel, which also includes an appearance from UFC fighter Michael ‘Venom’ Page.