Mike Sherry comes into the starting line-up as does Marcus Horan this time around, with the only other change in the pack being Dave Foley's inclusion instead of Billy Holland. It will be the young lock's first competitive start of the season.
In the backs, Tom Gleeson, a second half replacement for try scorer Simon Zebo in Glasgow last weekend, comes in for Barnes at outside centre.
Zebo slips to the bench to make way for Denis Hurley, the player he replaced against the Newport Gwent Dragons in the league opener when Hurley picked up a slight hamstring injury.
MUNSTER (v Scarlets): Johne Murphy; Doug Howlett, Tom Gleeson, Lifeimi Mafi, Denis Hurley; Ian Keatley, Peter Stringer; Marcus Horan, Mike Sherry, John Hayes, Dave Foley, Mick O'Driscoll, Peter O'Mahony (capt), Niall Ronan, James Coughlan.
Replacements: Denis Fogarty, Wian du Preez, BJ Botha, Billy Holland, Tommy O'Donnell, Duncan Williams, Scott Deasy, Simon Zebo.