Sam Hill and Gareth Steenson starred for Exeter in their win over London Irish, while Taqele Naiyaravoro was the hero for Northampton.
Munster put in a monumental effort, but Leinster's defence refused to buckle at Thomond Park.
Northampton Saints defeated Gloucester in a barnstorming contest at Franklin's Gardens, while Sale Sharks overcame Bath in the Premiership.
Saracens won a fifth straight Premiership match, though they are still far behind Leicester Tigers, who were defeated by Exeter Chiefs.
Northampton Saints made it four wins from five to go top of the Premiership, while Exeter Chiefs thrashed Wasps.
Racing 92, Northampton Saints and Connacht were all winners in Sunday's European Rugby Champions Cup action.
A looming points deduction would see Saracens facing a Premiership relegation battle this season, but they defeated Gloucester on Saturday.
A troublesome knee injury has ended Northampton Saints and England hooker Dylan Hartley's career at the age of 33.
Taqele Naiyaravoro impressed again as Northampton maintained their winning start to the Premiership season on Friday.
Northampton Saints claimed a win over the reigning champions at Allianz Park on the opening weekend of the Premiership season.
MMA promotion Bellator has signed former England rugby union star James Haskell, who is expected to make his debut in 2020.
Northampton Saints took the final Premiership play-off spot despite losing to Exeter, while Bath secured Champions Cup rugby next term.
James Haskell had looked to boost his Rugby World Cup chances at Northampton Saints but will now retire at the end of the season.
Having spent six successive years in the top flight, Newcastle Falcons were relegated from the Premiership on Saturday.
Anthony Watson was back in Premiership action on Friday, but Newcastle Falcons' time in the top flight looks to be coming to an end.
Worcester Warriors and Bristol Bears eased their relegation fears, leaving Newcastle Falcons needing a great escape to avoid the drop.