Pau moved to within one point of Worcester Warriors at the top of the group following a comfortable 21-6 victory at the Stade du Hameau.
The English outfit fielded a second-string side and it showed as the Frenchmen dominated from the outset, touching down in the opening minute through Colin Slade.
The former New Zealand international would be the defining factor in the contest and, after Jamie Shillcock had reduced the arrears through a brace of penalties, the fly-half crossed the whitewash for the second time.
There were 38 minutes remaining at that point but Worcester remained resilient until the latter stages of the contest when Julien Blanc completed the win – replacement Antoine Hastoy converting – for a 15-point triumph.
Grenoble proved too strong for Agen as they claimed a hard-fought 22-15 victory over their French rivals at Stade des Alpes.
The home side raced into a 12-0 lead thanks to tries from Mickael Capelli and Theo Nanette before Loris Tolot dotted down on the stroke of half-time for Agen. The visitors narrowed the gap when Fouad Yaha scored their second try early in the second half but an Adrien Latorre penalty on the hour-mark gave Grenoble a 15-10 lead.
Benito Masilevu then levelled matters but shortly afterwards the hosts claimed the win when Alexandre Dardet touched down, with Latorre converting.