The two retired NRL premiership stars have been on a collision course to square off in the ring ever since Gallen made his debut with the gloves in 2012, and football fans begged for the bout to happen.
Williams has since been accused of dodging Gallen, and last year the latter conceded the cross-code event that was little chance of happening.
Williams had his first fight in 2009 and has only had eight in total, although has won every one of those.
In June he had his first fight in six years, defeating Waikato Falefehi by unanimous decision.
