Richie McCaw could miss the World Cup final if he is deemed to have deliberately elbowed Francois Louw in New Zealand's 20-18 victory over South Africa.

The All Blacks captain struck Louw on the forehead 20 minutes into Saturday’s last four showdown at Twickenham, sending the openside flanker reeling with a blow that is sure to interest the citing officer.

Louw finished the match with two wounds to his forehead requiring a total of 20 stitches. When asked how he incurred the cuts, the Bath flanker said: “I’m not sure, I think it was at the bottom of a ruck”.

Striking with the elbow — which falls under law 10.4a of dangerous play and misconduct — has a low end sanction of a two-week suspension.

The citing officer has up to 36 hours after the match has ended to lodge a complaint, setting 6am on Monday morning as the deadline.

Following the semi-final win, New Zealand head coach Steve Hansen ahiled McCaw as an all-time great in the sport.

“We’ve probably got the greatest skipper and greatest player the All Blacks and maybe the world has had, without getting ahead of ourselves,” said Hansen, pointing to McCaw’s leadership as pivotal to the victory.

New Zealand will face either Australia or Argentina in the final with their Rugby Championship rivals meeting at Twickenham on Sunday.