Munster director of rugby Rassie Erasmus has suffered an early setback in his tenure after new signing Sam Arnold sustained a knee injury.
Speaking to the media on Wednesday, it was confirmed that Arnold has been ruled out of the opening period of the season with the problem.
However, there was some positive news over fly-half Tyler Bleyendaal (quad), who appears set to return to action at the end of the month.
Centre Francis Saili (shoulder) and flanker Peter O'Mahony (knee) are continuing to follow their respective rehabilitation programmes. It is unclear whether they will be fit to start the new campaign though, with Johnny Holland (hamstring) also currently under medical review.
Meanwhile, second-row Mark Chisholm has yet to return to training after sustaining a concussion against the Dragons in March's PRO12 game.