12 Dec, 14:42
Prop Cian Healy is expected to miss the start of the 2014 RBS 6 Nations after undergoing surgery on his injured ankle on Wednesday.
With concerns over Malcolm O'Kelly's knee injury as well as slight calf strains for both Frankie Sheehan and Rory Best, there are three hookers included in the squad as well as four second rows.
O'Sullivan said: "Malcolm's knee injury is still a concern for us and we have allowed some more time for it to respond further to treatment. Both Rory (Best) and Frankie (Sheehan) are carrying slight calf strains, so we have named three hookers to give us some back-up in that area."
The starting XV and replacements for the Welsh encounter will be named next Wednesday (January 31) at 12.45pm.
Neil Best (Belfast Harlequins/Ulster)
Rory Best (Belfast Harlequins/Ulster)
Simon Best (Belfast Harlequins/Ulster)
Simon Easterby (Llanelli)
Jerry Flannery (Shannon/Munster)
John Hayes (Bruff/Munster)
Marcus Horan (Shannon/Munster)
Denis Leamy (Cork Constitution/Munster)
Donncha O'Callaghan (Cork Constitution/Munster)
Paul O'Connell (Young Munster/Munster)
Mick O'Driscoll (Cork Constitution/Munster)
Malcolm O'Kelly (St. Mary's College/Leinster)
Frankie Sheahan (Cork Constitution/Munster)
David Wallace (Garryowen/Munster)
Isaac Boss (Ballymena/Ulster)
Girvan Dempsey (Terenure College/Leinster)
Gordon D'Arcy (Lansdowne/Leinster)
Denis Hickie (St. Mary's College/Leinster)
Geordan Murphy (Leicester)
Brian O'Driscoll (Blackrock College/Leinster) (capt)
Ronan O'Gara (Cork Constitution/Munster)
Peter Stringer (Shannon/Munster)
Andrew Trimble (Ballymena/Ulster)
Paddy Wallace (Ballymena/Ulster)