Munster director of coaching Tony McGahan admits Heineken Cup opponents Montauban are an unknown quantity after the draw for the first round of this year's tournament.
Reigning champions Munster launch the defence of their title with an opening night clash with the tournament newcomers on 10 October.
Montauban - who will become the 55th team to play Heineken Cup rugby - will immediately go under the spotlight against the 2006 and 2008 champions with Montauban's all-French clash with ASM Clermont Auvergne in the second round of games making Stade de Sapiac the 83rd venue to stage tournament action.
"Montauban will be a very interesting - and difficult - start for us and, at the moment, we don't know that much about them," said McGahan.
"However, they have done superbly well in the Top 14 in order to qualify for the Heineken Cup for the first time and there is absolutely no way we will be under-estimating them."
Leinster will open their campaign with a trip to Edinburgh on October 11. Stade Francais provide the opposition for Ulster in Ravenhill the same day.
Leinster will be at home the following week to London Wasps while Ulster will be away to Harlequins with Munster travelling to Sale on the Sunday.
England flanker James Haskell insists he will be pushing as hard as possible to be back from a toe injury in time to make his case for a spot in Eddie Jones' side looking to defend their RBS 6 Nations title next year.