Latecomers will be playing catch-up when they link-up with the rest of the British and Irish Lions squad early next week, head coach Warren Gatland has warned.
Mike Ross and Ian Madigan have been called into the Barbarians squad for the games against England and Ulster.
Munster expect to be at full strength for Saturday's Guinness PRO12 final against the Scarlets.
Billy Vunipola has been forced to withdraw from the British and Irish Lions squad for the upcoming tour to New Zealand due to a shoulder injury.
After playing his last home game for Munster in their Pro12 semi-final victory over Ospreys, the lock looked back on his 13-year career at the club.