Ireland flanker Sean O’Brien could be fit for the start of the Six Nations after undergoing surgery, while Robbie Henshaw will be out for up to six weeks with a hamstring injury.

O’Brien suffered a broken arm during the victory over Argentina and on Monday Leinster confirmed the British and Irish Lion had gone under the knife.

The 31-year-old will be out for between eight and 12 weeks, so may be back in time for the start of Ireland's Six Nations title defence at the Aviva Stadium on February 2.

Leinster team-mate Henshaw was ruled out of the historic victory over New Zealand on Saturday and faces at least a month on the sidelines.

Dan Leavy also missed the win over the All Blacks with a strained neck and will not face the United States in Dublin on Saturday.