Tyler Bleyendaal's four goals helped Munster to a priceless 20-16 away win at Nick Crosswell's Dragons.
In the Aviva Premiership, Leicester Tigers lock Mike FitzGerald scored a vital try to help his club to a tight 14-13 win at Newcastle, for whom Mike Delany kicked two goals.
Sean Maitland's Saracens beat the Northampton Saints of the Pisi brothers, Ahsee Tuala and Michael Paterson 27-12. Thomas Waldrom was at No 8 for the Exeter Chiefs in their 36-25 victory over Winston Stanley's Harlequins.
Dan Bowden turned out at second five for Bath, marking Jackson Willison of Worcester in a 37-22 win for the west country club.
Jimmy Gopperth was again at second five, and helping himself to 20 points, as Wasps hammered newly promoted Bristol 70-22. Jack Lam scored a try for the latter, while Tusi Pisi kicked two goals.
Prop John Afoa scored a rare try as Gloucester beat Sale Sharks 26-13.
In the French Top 14, Casey Laulala scored a brace and Dan Carter kicked five goals as Racing-Metro headed Ma'a Nonu's Toulon 41-30, while Tino Nemani wore the unfamiliar No 12 jersey as Grenoble crashed 46-9 to David Smith's Castres.
Conrad Smith went over for a try, and Colin Slade kicked five goals, as Pau beat Stade Francais 23-6, while Paul Perez's try was not enough for Toulouse who fell 25-20 to Lyon, who included Mike Harris, Toby Arnold, Rudi Wulf, Ti'i Paulo, Josh Bekhuis and Taiasina Tuifua in their line-up.
Romana Graham's La Rochelle, minus Victor Vito, were edged 29-28 by Brive.
Fritz Lee and Benson Stanley helped Clermont to a 40-16 win over Hugh Chalmers' Bordeaux-Begles, while Tanerau Latimer's Bayonne fell 21-9 to Montpellier.