Wales' Six Nations match against Ireland on 14 March will be refereed by Englishman Wayne Barnes after Australia's Steve Walsh withdrew due to "business commitments".
Barnes was due to be assistant referee for Italy's match against France on the same day and will be replaced by Wales' Nigel Owens.
Walsh was in charge when Wales thrashed England 30-3 in 2013.
Barnes has overseen four matches between Wales and Ireland.
Those game have yielded two wins for each side, with both Welsh victories contributing to Grand Slams in 2008 and 2012.
World Rugby has also confirmed New Zealand's Chris Pollock will no longer be assistant referee for Wales' match against Ireland and will be replaced by Jerome Garces of France.