John Hayes does not feature in the province's squad for the London Irish game. The veteran prop has been given the week off, but he will resume training with Munster on Monday.
Johne Murphy (hamstring) and Darragh Hurley (Achilles) are the other notable absentees. Murphy is optimistic about being back in readiness for the RaboDirect PRO12 opener against the Newport Gwent Dragons.
However, it may be two to three weeks before front rower Hurley is ready to resume.
The reason for the extended squad is because Munster also have an 'A' game against Connacht (kick-off 4.15pm), which is the curtain raiser to the senior friendly against Irish.
The composition of the respective squads will likely be decided on Wednesday although there is a provisional 16-man 'A' squad selected, which includes development, Academy and club players.
MUNSTER Squad (v London Irish) - Backs (14): Denis Hurley, JJ Hanrahan, Doug Howlett, Scott Deasy, Tom Gleeson, Sean Scanlon, Simon Zebo, Danny Barnes, Lifeimi Mafi, Tomas O'Leary, Duncan Williams, Peter Stringer, Ian Keatley, Declan Cusack.
Forwards (17): Wian du Preez, Stephen Archer, Marcus Horan, Peter Borlase, Mike Sherry, Damien Varley, Denis Fogarty, Ian Nagle, Dave Foley, Mick O'Driscoll, Billy Holland, David O'Callaghan, Niall Ronan, Tommy O'Donnell, Peter O'Mahony, Paddy Butler, James Coughlan.
MUNSTER 'A' Squad (v Connacht 'A): Dave Kilcoyne, James Ryan, Sean Henry, James Cronin, Christy Condon (Dolphin), Philip Donnellan (UCC), Liam Og Murphy (Young Munster), Brian Hayes, Brian O'Hara, Cathal Sheridan, Gareth Quinn McDonogh, Corey Hircock, Gerry Hurley (Cork Constitution), Luke O'Dea, Ivan Dineen, Ronan O'Mahony.