Jeff Horn was fighting Samuel Colomban for the vacant Australian welterweight title in his fifth professional bout on Thursday.
Horn turned professional last year after losing in the quarterfinals of the 2012 Olympics in the light welterweight division.
The 25-year-old, known as The Hornet, has something of a buzz around him, but no one at The Melbourne Pavilion expected what happened in the first round against Colomban.
Horn produced a monster right hand just 76 seconds into the fight to claim the belt. Is it a contender for Knockout of the Year? You be the judge.