London Irish did run riot in their 69-26 win over Mont de Marsan at the Madejski Stadium in Round 2, with wing Topsy Ojo crossing for two of their 11 tries, but the damage to their last eight hopes was done in last month's contests with Gloucester.
The Exiles, who went within touching distance of the trophy when they were pipped 36-34 by Gloucester in extra time of the final at the Twickenham Stoop also face a battle to hand onto some of their leading players.
Brian Smith has admitted that the club will struggle to hold onto Alex Corbisiero and Jonathan Joseph for next season.
Both England internationals are products of the Exiles academy, but with limited resources compared to their league rivals and currently in the midst of a relegation battle, the signs do not look promising.
- London Irish ran up 69 points in the reverse fixture earlier this season, the most Mont-de-Marsan have ever conceded in Europe.
- Mont-de-Marsan defeated French league rivals Bordeaux-Begles in rounds three and four, the consecutive victories coming on the back of 11 straight defeats in this tournament.
- Mont-de-Marsan's Thibault Duvallet is one of three players to have a 100% goal-kicking success rate having attempted five or more shots at goal (6/6).
- London Irish's Anthony Watson is the tournament's top metre-maker. He has made 334 metres from 23 carries.