Connacht 16 Bayonne 13:Connacht got their Pool One campaign back on track and did Harlequins a favour at the same time by beating Bayonne 16-13 in Galway.
Seán Cronin and Gavin Duffy touched down in either half, while Ian Keatley adding two goals.
A try from replacement hooker David Roumieu, converted by Jean-Baptiste Peyras, set up a nail-biting climax at the Sportsground but the hosts managed to hold on.
In the Heineken Cup, Shane Williams weaved his magic with a spectacular try that grounded London Irish and gave the Ospreys a 27-16 victory in Pool Three.
Williams' scintillating solo score helped inflict only a second defeat of the season on Aviva Premiership leaders Irish, who began their campaign with a win over Munster last week.
The visitors could have few complaints after Irish wing Tommy Bowe claimed an early touchdown before outhalf Dan Biggar kicked four penalties.
Centre James Hook, who moved to 10 when Biggar went off injured early in the second period, added a conversion and penalty, while Irish mustered a Sailosi Tagicakibau interception try, plus 11 points from Ryan Lamb.
Castres defeated Cardiff Blues 27-20 to edge ahead of the Welsh side at the top of Pool One.