Holders Munster maintained their unbeaten record in the European Cup at their Thomond Park stronghold with a 41-23 thrashing of Bourgoin that left them on course to qualify for the quarter-finals.
After last weekend's hard-fought 21-19 victory away to Leicester, the Irish province made it two wins out of two on Saturday as they ran in six tries to the delight of their passionate home crowd.
But it was a different story for former champions Wasps who saw the pain of a 19-12 defeat away to French side Perpignan compounded by an injury to England international Josh Lewsey which threatens the back's participation in the Twickenham Test match against World Cup favorites New Zealand on Sunday week.
Lewsey, who can play on either the wing or at full-back, left the Stade Aime Giral with his knee in a brace and now must come through a scan if he is to face the All Blacks.
His exit in France was the last thing world champions England's head coach Andy Robinson needed having already lost through injury the likes of backs Jonny Wilkinson, Olly Barkley and Stuart Abbott, as well as second-row forward Steve Borthwick ahead of the Nov. 5 meeting with New Zealand.
"I will have to wait and see what the scan says, but I am being as positive as possible," Lewsey said. "It was a twist, it was one of those things you can't predict, and the pain wouldn't go away when I was trying to run at top end."
"My gut feeling is that is it not as bad as it looks, but we will just have to wait and see. I might be training by next Tuesday or Wednesday, I just don't know," Lewsey added.
Perpignan lock Colin Gaston's second-minute try proved the decisive score in this Pool Two fixture.
Elsewhere French side Agen enjoyed a 32-26 win away to Gloucester despite gifted Cherry and Whites center Anthony Allen celebrating his call-up into the England squad with two tries.
Victory for Agen, their second in as many Pool Two matches, owed much to tries from Arnaud Mignardi, Pieter Van Niekerk, Thomas Soucaze and a bonus point score from Conrad Stoltz.
Agen fly-half Jerome Miquel's three conversions and a penalty also proved important.
England World Cup-winning hooker Steve Thompson's try helped Northampton to a 37-13 win against Border Reivers at Franklin's Gardens while Biarritz Olympique, last season's beaten finalists, thrashed Italian minnows Overmach Parma 50-7.
Biarritz ran in seven tries.
France international scrum-half Dmitri Yachvili scored two tries and slotted four conversions and a penalty as the visitors comfortably claimed their second win in as many Pool Six matches.
Eighth man Thomas Lievremont, whose season has been disrupted by a recurrent thigh injury, scored a try on his comeback.