Sam Costelow, 25, suffered an ankle injury in the second half of the 26‑23 defeat by Scotland and is unfit to travel to Dublin. He was retained in the squad last week but will miss the Ireland match; Jarrod Evans or Dan Edwards will take his place.
Coach Steve Tandy will name the team on Wednesday and also replace injured flanker Taine Plumtree. Wales have lost 24 of 26 internationals and seek to end a 14‑match Six Nations losing streak.