English referee Wayne Barnes has been appointed to take charge of the key RBS 6 Nations clash between Ireland and Wales in Cardiff on 14 March.
Barnes will replace Australia's Steve Walsh, who World Rugby announced had withdrawn from the game because of business commitments.
In a further change ahead of the Millennium Stadium encounter, New Zealand's Chris Pollock has been replaced as one of the assistant referees by Frenchman Jerome Garces.
Barnes had initially been appointed as an assistant official for Italy versus France on March 15, but Welshman Nigel Owens will now take over from him in that role.
