And continuing the successful development of young players, Cork Constitution prop John Ryan, who featured in their Ulster Bank League game last weekend against Clontarf, has been named on the Munster replacements bench.
The 23-year-old comes onto the bench in place of the injured Marcus Horan who failed a late fitness test having picked up an ankle injury in training this week.
The province's selected side shows five changes to the one that started against Leinster last time out, two in the back-line and three up front.
Denis Hurley, who played for UCC last weekend, comes onto the left wing in place of the injured Keith Earls (knee).
Barnes, an early replacement for Earls against Leinster, retains the number 13 jersey ahead of Heineken Cup newcomer Will Chambers who has been kept in reserve.
It is in the pack that the big calls have been made with Donncha O'Callaghan and Denis Leamy both relegated to the bench in favour of O'Mahony and James Coughlan.
O'Callaghan gives way to fellow Ireland Rugby World Cup squad member Donnacha Ryan, who moves up from the blindside flank he occupied against Leinster to partner captain Paul O'Connell in the second row.
MUNSTER (v Northampton Saints): Johne Murphy; Doug Howlett, Danny Barnes, Lifeimi Mafi, Denis Hurley; Ronan O'Gara, Conor Murray; Wian du Preez, Damien Varley, BJ Botha, Donnacha Ryan, Paul O'Connell (capt), Peter O'Mahony, Niall Ronan, James Coughlan.
Replacements: Denis Fogarty, John Ryan, John Hayes, Donncha O'Callaghan, Denis Leamy, Tomas O'Leary, Ian Keatley, Will Chambers.