The dual code rugby star demolished AFL great Hall overnight in Australia, dominating from the opening seconds.
Williams jolted the Sydney Swans premiership winner in the first half minute with some crisp accurate shots.
Hall was down after just 47 seconds, though referee Les Fear said he didn't see a punch.
It looked like Hall had been hit with a left hook and he appeared unsteady after standing up.
Within 40 seconds, the 45-year-old returned to the canvas after taking a couple of big shots,