Francis Saili's Munster beat Nick Crosswell's Dragons 26-5 and Leinster, with Isa Nacewa and Hayden Triggs in the squad, edged Ma'afu Fia's Ospreys 19-16.
Two goals by fullback Jayden Hayward were not enough as Treviso went down 24-15 to Scarlets, who again had Michael Collins (15), Regan King (13) and Hadleigh Parkes (12) in their backline.
No 8 Nick Williams scored two tries as his Ulster shut out Mils Muliaina's Zebre 32-0.
Glasgow defeated Cardiff Blues, with Jarrad Hoeata and Rey Lee-Lo, 27-20.
In the French Top 14, a try to Joe Rokocoko and five goals to Dan Carter saw Racing-Metro back to the top of the table with a 38-13 win over Agen. Ben Tameifuna came off the bench but was yellow-carded, though the Chiefs could do with him about now. George Tilsley scored Agen's sole try.
La Rochelle, who fielded Romana Graham and Hikairo Forbes, sprung a surprise in beating Toulon 19-14. Tom Taylor scored a late try for the latter.
Another late try by another former All Blacks No 10, Luke McAlister, enabled Toulouse to get up for a 21-21 draw with Brive.
Peter Saili scored a try and replacement Simon Hickey a conversion as Bordeaux-Begles moved into fourth position with a 48-20 shellacking of Oyonnax.
Pau eased clear of relegation with a 19-12 win over defending champion Stade Francais, Colin Slade slotting a penalty goal. Conrad Smith (13) and Daniel Ramsay (5) both started for Pau.
Grenoble, despite a brace to No 8 Rory Grice, were hammered 45-12 by Clermont, who had Isaia Toeava and Fritz Lee in their ranks.
