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.
Munster returned to winning ways in the United Rugby Championship a month on from Graham Rowntree’s departure with a 17-10 victory.
Veteran scrum-half Conor Murray has returned home to Ireland midway through Munster's tour of South Africa for personal reasons.
The veteran back-rower and tighthead Oli Jager were starters in last Saturday’s rain-sodden win over Ospreys.