Another two players, David Gibson and Sam Tuitupou, were banned for two weeks after the incident in last Saturday's Auckland v Canterbury Super 12 match.

Lock Williams admitted rucking McCaw, claiming he was lying in a position which impeded Auckland's access to the ball.

Tuitupou and Gibson admitted going for the player, rather than the ball but were given lighter penalties after being adjudged to have rucked McCaw's back rather than his head.

With on-field discipline sure to play a key part in results against the Lions, coach Graham Henry will have to decide whether Williams can be trusted to keep his cool in the three-Test series.