How to do a Knee Slam in freestyle football / soccer. For more details about this move follow the steps below -

STEP 1 - Do a footstall and kick the ball lightly upwards

STEP 2 - Bring your foot backwards and knee downwards to hit the ball into the ground (strong foot)

It can also be performed while juggling and can also be used as a flick up for picking up the ball from the ground