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.
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 tighthead prop Stephen Archer has signed a contract extension with the province alongside centre Alex Nankivell.
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.
Munster returned to winning ways at a rain-lashed Virgin Media Park by beating Ospreys 23-0 in a repeat of last season’s BKT United Rugby Championship quarter-finals.
New signing Billy Burns is set to make his Munster debut against Bath later today in a pre-season friendly at The Rec.