EE WAS REMOVING A DRIVE BELT FROM THE CRUSHER JAW, WHILE PULLING DRIVE BELT LOOSE FROM THE GUARD, HIS LEFT FOOT WAS ON SLOPING PORTION OF THE CATWALK,PERPENDICULAR TO SLOPE. HIS ANKLE ROLLED OVER & HE IMMEDIATELY FELT IT. HE REPORT TO FILL IN FORMAN BUT DIDN'T FEEL NEED FOR MEDICAL HELP UNTIL FOLLOWING AFTERNOON, WHEN EXPERIENCED SWELLING PAIN