Jamaal Charles was ALMOST attacked by a humongous spider ... but fortunately for the ex-NFL star -- he's still got some moves, and ducked away from the big-ass arachnid as it charged!!!
It all went down in the former Kansas City Chief's backyard ... where he was trying his best to capture an 8-legged beast and protect his Texas home.
The video is pretty intense ... Jamaal tries to calmly sweep the spider into a box -- but then it suddenly darts at his left leg!!!
But, the ex-running back is able to move out of the way .