Noah Caluori scored four tries as Saracens overwhelmed Newcastle 73-14 at StoneX Stadium.
Two-time European winners Munster were dumped out of the Champions Cup at the pool stage for just the fourth time since 1998 as they were stunned by Castres at Thomond Park 31-29.
Adam Radwan scored two tries as Leicester kept in contention for a play-off spot with an impressive 36-28 win over Saracens.
Greg Fisilau inspired a resurgent Exeter to a 24-10 Gallagher Premiership win over Leicester Tigers, moving them within a point of league leaders Northampton Saints.
Harry Byrne's goal-kicking proved the difference as an error-strewn Leinster held off a determined Leicester to claim a 23-15 victory in the Investec Champions Cup.
An astonishing start which saw Bath 28-0 ahead inside 19 minutes proved crucial as the Prem side saw off Munster 40-14 in their Champions Cup opener.
Exeter came from 26-6 down to secure a dramatic 27-26 win and inflict a rare home defeat on Sale as the Gallagher PREM resumed.
Leicester Tigers eked out a 36-35 win against Sale Sharks as Bath, Harlequins and Exeter all won by big scorelines in Saturday's Gallagher Prem action.