Leinster coach Joe Schmidt admits they need a "miracle" to make the knockout stages of the Heineken Cup.
The reigning champions were beaten 28-21 by Clermont in Dublin, making it back-to-back defeats to the French giants who have booked their spot in the quarter-finals.
Leinster can still reach the last eight but need an unlikely sequence of results to go their way.
"Miracles happen in sport, I guess, but mathematical long shots very seldom come into being," admitted the New Zealander.
"I don't think we have the same depth as some of the big-spending French clubs. It's hard to take defeat two weeks in a row, with the amount of effort the players put in.
"The other challenge for champions is they always look pretty good when they are on top. It is how they come back from adversity that is the real challenge."
Clermont head coach Vern Cotter is determined that this will finally be their year in the competition, having suffered semi-final heartbreak to Leinster last year.
Speaking after another pulsating clash, Cotter said: "We intend to go the whole way. It's a game of rugby - it doesn't always go the way we want, but our intention is to go as far as we can.
"Last year we lost a semi-final in Bordeaux. We didn't get a crack at the final. We would like to get there and see if we can get over the line and take the title. That is our firm intention."
Although Clermont celebrated with their fans in the stadium after ending a run of five defeats on Irish soil over a five-year span, Cotter will keep his players' feet on the ground.
"All the criteria that is important for a top performance - technical, tactical, physical, psychological - I thought we were present in all those sectors," he added. "Without getting too carried away, we are reasonably happy."