Uncapped second row Andrew Coombs, from the Dragons, also gets the nod from interim head coach Rob Howley, stepping up in the absence of injured trio Bradley Davies, Luke Charteris and Alun Wyn Jones.
There was some good news however for Howley with Ian Evans fit to start alongside Coombs.
Adam Jones returns from injury in the front row, lining up alongside British and Irish Lions colleagues Gethin Jenkins and Matthew Rees.
Howley has also stuck with the three-quarter line that helped Wales to the Grand Slam last year, Jamie Roberts and Jonathan Davies in the centres and Leigh Halfpenny, George North and Alex Cuthbert making up the back three.
Sam Warburton will lead the team in an unchanged back row alongside Toby Faletau and Aaron Shingler.
On the bench Harlequins second row Olly Kohn could make his international debut, but exciting youngster Eli Walker misses out due to injury.
And despite coming into the game on the back of a difficult recent run, Howley insists the Grand Slam champions are in good spirits.
"As a squad we have worked hard over the past two weeks and go into Saturday excited and confident at defending our title," said Howley.
"It's a boost to have Adam and Ian return from injury and it's a great opportunity for Andrew who has been performing well at regional level to show what he can do on this stage.
"The Six Nations is all about momentum and we know we have to hit the ground running against Ireland."
15 Leigh Halfpenny (Cardiff Blues)
14 Alex Cuthbert (Cardiff Blues)
13 Jonathan Davies (Scarlets)
12 Jamie Roberts (Cardiff Blues)
11 George North (Scarlets)
10 Dan Biggar (Ospreys)
9 Mike Phillips (Bayonne)
1 Gethin Jenkins (Toulon)
2 Matthew Rees (Scarlets)
3 Adam Jones (Ospreys)
4 Andrew Coombs (Dragons)
5 Ian Evans (Ospreys)
6 Aaron Shingler (Scarlets)
7 Sam Warburton (Cardiff Blues) Captain
8 Toby Faletau (Dragons)
16 Ken Owens (Scarlets)
17 Paul James (Bath)
18 Craig Mitchell (Exeter)
19 Olly Kohn (Harlequins)
20 Justin Tipuric (Ospreys)
21 Lloyd Williams (Cardiff Blues)
22 James Hook (Perpignan)
23 Scott Williams (Scarlets)