Hayes, O'Callaghan and Wallace are named in the starting line-up along with Frank Sheahan and Peter Stringer who both came on as second half replacements last time out in the game against Ospreys, while Flannery, Horan and Leamy are listed among the replacements.
All told there are eight changes, two positional, to the side that started that day in the Liberty Stadium, Rua Tipoki moves to number
13 with Lifeimi Mafi wearing the number 12 shirt and the return of John Hayes sees Tony Buckley switch to loosehead prop.
Elsewhere, O'Callaghan takes over from Mark Melbourne who is named on the bench, Niall Ronan earns a well deserved breather with Wallace getting the openside berth in a side that once again will be led by Anthony Foley winning his 184th competitive Munster cap.
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