Shaka1eye
Reserve Grader
Offside is ruled in relation to the ball. Forget the player with the ball in hand, it is the loaction of the back most part of a player in relation to the ball.
So in this case, if the ball is on the 10 meter line, assuming a player is running, the very back part (the foot) of the chasing player need to be behind the ball, aka the 10 meter line.
When the blokes in the bunker check for offside I always thought they looked at the position of the feet on the ground. Anyway, here's the rule from the NRL website;
'A player is offside if he has one foot (either on or off the ground) in front of a teammate who ‘last touches, is touched, held or kicked the ball’.