No athlete can match the fast feet of Marshawn Lynch -- not even Cristiano Ronaldo ... says the footwork specialist whose trained both. 

Beast Mode just got in some drills with Luis Badillo Jr. (AKA the dude with the world's fastest feet) up in the Bay ... and Marshawn straight-up wrecked his course IN THE SAND.

Badillo couldn't believe what he was seeing -- telling TMZ Sports the Raiders RB had the best footwork of any sports star he's ever worked with ... including Ronaldo and Olympic sprinter Asafa Powell. 

Feet Mode -- activated.

NFL defenses -- screwed. 

QUICK SAND