They lie 11th in the French Top 14 with Amlin glory the only avenue left open to them extending their presence among the elite of European clubs.
"They are going to be tough opponents but we like to think we will be a handful ourselves," said Leinster star centre Brian O'Driscoll.
"Looking at some of their video footage they look like a side who should be much further up the league than in 11th place in the Top 14.
"We know they have got some very, very talented players - guys who we have known and played against for years.
"And any team that has managed to be in the Heineken Cup year after year coming out of the French league has to be pretty good going."
Leinster, the triple Heineken Cup champions, are bidding for a fourth European final in the space of five seasons but will be wary of a Biarritz side who stunned Gloucester 41-31 in the Kingsholm quarter-final and will be fighting for their elite European lives.