"Unfortunately we have to believe it," said Leinster Head Coach, Joe Schmidt, who joined the Irish club from Clermont and has guided Leinster to back-to-back Heineken Cup crowns.
"We will also be against the Scarlets and Exeter Chiefs in Pool 5 so it is a tough group. Clermont are an exceptional and extremely well coached side - they have quality across the board.
"They had a couple of injuries ahead of last season's semi-final in Bordeaux, and then lost Lee Byrne and Julien Malzieu during the game, so perhaps we had a bit of good fortune on that occasion.
"The Scarlets have some super players and will also be really challenging opposition, particularly through the likes of George North, Jonathan Davies and Rhys Priestland.
"And coach Rob Baxter has done a great job with Exeter Chiefs, first getting them promoted and then taking them storming through the English league and into the Heineken Cup for the first time."
Ulster Rugby, beaten in the 17th tournament final by Leinster at Twickenham Stadium last month, are up against former champions Northampton Saints, Glasgow Warriors and Castres Olympique.
"There are plenty of connections between the clubs," said David Humphreys, Ulster's Director of Rugby. "We know Glasgow really well from our league meetings and we played the Saints in the 2011 quarter-finals - plus Roger Wilson has rejoined us from Northampton while Pedrie Wannenburg has left us for Castres.
"There are a couple of really tough, highly competitive groups and that shows the standard across Europe and that will certainly make for another very interesting tournament."
Former double champions, Munster Rugby, are in with last season's semi-finalists Edinburgh Rugby, Saracens and Racing Metro 92 in Pool 1, while Connacht Rugby will be up against Amlin Challenge Cup champions Biarritz Olympique, Aviva Premiership champions Harlequins and new Italian club Zebre in Pool 3.