But they got back to winning ways, and ripped up the formbook, on the weekend with a 39-17 victory over Northampton Saints.
Topsy Ojo said: "It was great to get the win - it was well needed.
"It would be nice to kick on in the Premiership but the Challenge Cup provides us with an opportunity to progress as a team and we can build momentum."
The Exiles are regulars in the Amin Challenge Cup but European silverware has so far eluded them with a runners-up medal in 2006 their best effort.
Bordeaux have also struggled in the open weeks of action in France and lie in the same league position as London Irish. They go into the clash on the back of three losses.