The UCD man is one of just two players from last year's squad that finished fifth in the World Championship in South Africa last year – Ireland's best finish at the tournament – named in the side. Ulster's Stuart Olding is the other.
McGrath is partnered at half-back by Stephen Crosbie, who has featured regularly for Old Belvedere in the AIL; Olding, more recognised as a No 10, starts at full-back.
The Irish management team expects the Belfast Harlequins man to be called up to Pro12 action by his province at some stage and he deputises at No 15 as Connacht duo Robbie Henshaw (unavailable) and Darragh Leader (injured) are ruled out.
There is also an injury crisis at loosehead, with three options unavailable, meaning Brian Scott shifts over from his preferred tighthead.
Still, coach Mike Ruddock declared himself pleased with preparations.
Wales are a more experienced bunch. They managed a third-place finish at the Junior World Championship last year and include five of that squad in their starting XV.
There is no place for the much- heralded out-half Rhys Patchell in the squad. Patchell started as Cardiff beat Munster at Thomond Park in the Pro12 and he looks like he'll be used by the region in the coming weeks.
Ireland – S Olding; A O'Meara, T Daly, R Scannell, R Scholes; S Crosbie, L McGrath (capt); B Scott, G McGuigan, C Taylor; J Donnan, G Thornbury; P Timmins, R Murphy, C Joyce Reps: J Andrew, P Dooley, J Caulfield, S McCarthy, J Van Der Flier, J Creighton, D Sweetnam, D Panther
WALES – D Jones; A Evans, C Allen, S Hughes, A Hewitt; S Davies, R Williams; N Smith, E Dee, N Thomas, C Jones, Rhodri Hughes, S Bennett, D Thomas, E Jenkins (capt) Reps: E Lewis, G Thomas, D Suter, J Jones, J Benjamin, J Davies, E Davies, T Pascoe.