Ulster have confirmed that Rory Best suffered a fractured arm during Ireland's dramatic defeat to New Zealand on Sunday.
The hooker was forced off after scoring his country's second try in their 22-24 loss to the All Blacks in Dublin.
The 31-year-old is now expected to spend time on the sidelines as he recovers.
Ireland came within seconds of ending New Zealand's unbeaten record in 2013 before a last-gasp try and conversion earned the visitors the win.