Dublin - Caelan Doris will miss Ireland's Six Nations clash with reigning Grand Slam champions Wales because of a head injury, with Peter O'Mahony recalled to Andy Farrell's starting line-up on Tuesday.
Back-row Doris is subject to return-to-play protocols after being forced off inside five minutes of his international debut during Saturday's win over Scotland.
"Caelan has had a bit of a knock previously this year and we thought we were doing the right thing by the kids," Farrell said of the 21-year-old.
The Ireland boss said the performance of veteran O'Mahony, who came on for Doris, meant he had few qualms about starting the 30-year-old.
"I thought he did really well when he came off the bench," he said. "I thought he had been outstanding all week in training and it rolled over into his performance."
Farrell's other change to his starting XV for the visit of Wayne Pivac's men is to bring in Robbie Henshaw at outside centre in place of the injured Garry Ringrose.
Ringrose was taken off at half-time against the Scots with a hand problem and has also been ruled out of Ireland's trip to face England at Twickenham later this month.
Farrell's enforced reshuffle means Leinster back-row Max Deegan could make his debut from the bench, while wing Keith Earls is also included among the replacements.
With Doris unavailable for Saturday's match in Dublin, CJ Stander switches to replace him in the number-eight position, with the experienced O'Mahony coming in to win his 66th cap at blindside flanker.
15 Jordan Larmour, 14 Andrew Conway, 13 Robbie Henshaw, 12 Bundee Aki, 11 Jacob Stockdale; 10 Johnny Sexton (captain), 9 Conor Murray, 8 CJ Stander; 7 Josh van der Flier, 6 Peter O'Mahony, 5 James Ryan, 4 Iain Henderson; 3 Tadhg Furlong, 2 Rob Herring, 1Cian Healy
Substitutes: 16 Ronan Kelleher, 17 Dave Kilcoyne, 18 Andrew Porter, 19 Devin Toner, 20 Max Deegan, 21 John Cooney, 22 Ross Byrne, 23 Keith Earls
Coach: Andy Farrell (ENG)