The situation every defender is dreading in 2021 Geelong defender Lachie Henderson says some passages of play will be ‘undefendable’ under new man on the mark rules AFL by JON RALPH Premium Content Subscriber only Geelong defender Lachie Henderson says the league's new man-on-the-mark rule will make some passages of play "undefendable" and believes scoring will only increase as a result. The new rules allow the defender closest to the player who has marked a short period to decide whether to immediately retreat before being told to "stand" by the umpire. Henderson says if a supporting player charges into space inside 50m with no other defender in sight, the defender will just have to stand and watch while it is kicked to them.