10 Dec, 12:23
Ireland's John Lacey will referee his first ever RBS 6 Nations match in February, while Alain Rolland is also included in the Elite Panel in what is his last season.
Horan turned out for Munster last Friday night for their game with Gwent Dragons and he came through that unscathed.
Murphy played for Leicester at the weekend and although O'Callaghan had no run-out it is expected that he will be included among the replacements for Saturday's clash.
The one doubt that remains concerns Peter Stringer who attended the game in Thomond Park on Friday with his wrist in plaster but the cast is expected to be removed today and a decision made on his availability.