New Zealand hooker Andrew Hore has been slapped with a five-week ban for striking Bradley Davies during last weekend's win over Wales.
Welsh lock Davies needed hospital treatment for severe concussion after being knocked unconscious by Hore in the opening minutes.
Hore appeared in front of an IRB hearing in Bristol on Wednesday, where he pleaded guilty to the offence.
An IRB statement read: "The Judicial Officer held that the act of foul play was inherently dangerous, being a deliberate swinging of the arm, delivered with significant force, causing serious injury to the victim player, Bradley Davies, who was unsighted.
"However, the Judicial Officer found that the player had not intended to make contact with the victim player's head.
"In categorising the seriousness of the offence the Judicial Officer held that it was worthy of a top end entry point under the IRB's sanctions table, and that the entry point should be eight weeks.
"The Judicial Officer held that there were no aggravating factors, and acknowledged the mitigating factors of acceptance of guilt by the player, his genuine remorse, as evidenced by his daily contact with the injured player, his exemplary disciplinary record, and his conduct throughout the hearing and imposed a suspension of five weeks."
Hore will miss the All Blacks' final autumn Test against England on Saturday and be unavailable for Super 15 side the Highlanders for any pre-season matches.
The 34-year-old forward is suspended until February 24 and has the right of appeal.
All Blacks assistant coach Ian Foster, Hore himself and his legal team impressed upon Professor Crerar the importance of the Highlanders' pre-season friendlies.
The statement continued: "The judicial officer received unreserved assurances from Ian Foster, assistant coach, New Zealand, the player and his legal representative that the pre-season matches to be played by the Highlanders during the weekends of February 1, 8 and 15 all had significant and meaningful consequences for the player in accordance with IRB regulation 17."
Hore revealed he had spoken with Davies since the incident.
"I want to say how bad I feel and how embarrassed I am to be in this situation," he told the New Zealand Herald.
"It is not the All Black way and I have let myself down and the team and probably the whole country is pretty proud of what we do.
"I hope Bradley Davies does recover and get back up and running and play in the Heineken Cup as soon as he can.
"I have been on the phone and talked to him on Sunday about the incident and obviously the All Black management and the leader group that I am a part of has been pretty stern on me for getting us into this situation and I have to take what I have got and go back and start building a reputation as a good, clean, hard footy player and hopefully I can do that in the next Super Rugby competition when I get back playing."
Is a five-week ban sufficient punishment for Andrew Hore?