A thrashing of Lyon ensured Leinster made it five wins from five in the European Champions Cup, while Racing 92 reached the last eight.
High-flying pair Lyon and Bordeaux Begles celebrated contrasting victories in Top 14 action on Saturday.
Fiji forward Leone Nakarawa will return to Glasgow Warriors for the rest of the season, subject to obtaining a visa and passing a medical.
There were wins for Lyon and Racing 92 in the Top 14 as Bordeaux-Begles were usurped at the summit.
Juan Imhoff scored two of Racing 92's six tries as they beat Ospreys 40-27 to increase their lead at the top of Pool 4.
There were seven tries in Leinster's 43-16 European Champions Cup win over Northampton Saints as they made it 10 victories from 10.
Leone Nakarawa has been linked with a return to Glasgow Warriors after Racing 92 announced they had sacked their star lock on Friday.
Lyon's lead at the Top 14 summit was reduced to just one point as they were comprehensively beaten 33-8 by Montpellier on Saturday.
Ospreys were no match for Saracens on Saturday, while Exeter Chiefs were among the other European Champions Cup winners.
Racing 92, Northampton Saints and Connacht were all winners in Sunday's European Rugby Champions Cup action.