Munster picked up a signature Champions Cup win as they downed Saracens 17 - 12 in an old school tussle at Thomond Park.
There is no return for O’Mahony, whose last appearance came in the December 13 defeat at Castres.
Ahead of the highly anticipated URC matchup between Leinster and Munster, both teams have welcomed back multiple players to their starting lineup.
Munster Rugby secured a 33 – 7 victory over Stade Francais at Thomond Park to get their Investec Champions Cup campaign off to the perfect start.
Veteran scrum-half Conor Murray has returned home to Ireland midway through Munster's tour of South Africa for personal reasons.
Munster player ratings: Munster lost 26 - 12 to rivals Leinster in front of a league record 80,000-plus fans at the iconic Croke Park stadium in Dublin.
Leo Cullen’s unbeaten URC table-toppers defeated Benetton 35-5 last weekend in Italy and they have altered their line-up with two changes in the pack and one in the backs.
Zebre Parma made history by securing their first-ever victory over Munster with a 42-33 bonus-point win in the United Rugby Championship.