Leinster have been drawn with their European conquerors La Rochelle in the Heineken Champions Cup pool stages next season.
But Munster will fancy their chances of retaining their top seed status into the knock-out stages after the draw was made at the Tottenham Hotspur Stadium this afternoon.
Leinster's quest for a fifth star on their jersey has been wrecked by Ronan O'Gara's Stade Rochelais side in each of the last three seasons - in the 2021 semi-final and in the last two finals.
READ MORE: Leinster pulling for Euro conquerors La Rochelle to win Top 14 with top seeding on the line
And, after also failing to regain the URC crown last season, Leo Cullen's charges pay the price for their tier two seeding by finding themselves in a tough pool that also includes the Stormers - the URC champs and runners-up in the last two years - as well as Stade Francais, Leicester Tigers and Sale Sharks.
However Leinster will not face the Stormers as both play in the URC.
Munster's status as URC champions made them one of four tier one clubs in the draw, along with Saracens, Toulouse and defending champs La Rochelle.
The competition format has changed for next season to four pools of six teams and Graham Rowntree's charges have been drawn against the new French side Aviron Bayonnais in Pool 3.
Munster have also drawn 2020 champions Exeter Chiefs, plus three-time winners Toulon - the reigning Challenge Cup champions - Northampton Saints and Glasgow Warriors, but the Reds will not face their old rivals as both compete in the URC.
In Pool 2, Ulster will look to revive their fortunes after a very disappointing last campaign against newly-crowned Top 14 champions Toulouse - who beat La Rochelle in Sunday's Grand Final - as well as Cardiff, Bath, Harlequins and Racing 92, who will have Stuart Lancaster as their new head coach after his seven year stint with Leinster.
Ulster won't face Cardiff, with both clubs competing in the URC.
Connacht's return to the competition will see them pitted against former head coach Pat Lam's Bristol Bears in Pool 1, along with Premiership champs Saracens, Union Bordeaux Begles, the Bulls and Lyon.
With the Bulls in the URC, the westerners won't play them in the pool stages.
The tournament will get underway on December 8, with both European finals to be played at the Tottenham Hotspur Stadium in London next May.
CHAMPIONS CUP
POOL 1: Saracens, Union Bordeaux Begles, Bulls, Bristol Bears, Connacht, Lyon
POOL 2: Toulouse, Cardiff, Bath, Racing 92, Harlequins, Ulster
POOL 3: Munster, Aviron Bayonnais, Glasgow, Exeter Chiefs, RC Toulon, Northampton
POOL 4: La Rochelle, Stade Francais, Leicester Tigers, DHL Stormers, Leinster, Sale Sharks
CHALLENGE CUP
POOL 1: Invitee 1, Section Paloise, Dragons, Zebre Parma, Cell C Sharks, Oyannax Rugby
POOL 2: Ospreys, USAP, Newcastle Falcons, Emirates Lions, Montpellier, Benetton Rugby
POOL 3: Edinburgh, Castres Olympique, Clermont Auvergne, Invitee 2, Gloucester, Scarlets
