Swift kick to the shin He'll instinctively want to lower his body in order to try and protect it. As he does so, poke him in the eye; use your knuckles at the second joint of your hand and strike the throat. It's not about power or strength. It's about surprise and shock !
Stay low and go for his knees would be your best bet. Hard kick to the side of the knee could knock him to the ground. Mostly depends upon your abilities though.
SW-User
Tell him to count to five - and kick him in the balls on 2