Sam Hill and Gareth Steenson starred for Exeter in their win over London Irish, while Taqele Naiyaravoro was the hero for Northampton.
Long-serving Glasgow Warriors lock Jonny Gray will leave Scotstoun to join Premiership leaders Exeter Chiefs.
An ankle fracture is expected to sideline Henry Slade for up to two months, making him unlikely to be fit for the start of the Six Nations.
Saracens mounted a late push but were unable to avoid losing to Exeter Chiefs at Sandy Park.
Saracens won a fifth straight Premiership match, though they are still far behind Leicester Tigers, who were defeated by Exeter Chiefs.
Brothers Joe and Sam Simmonds were influential as Exeter Chiefs moved to the brink of a quarter-final spot in Europe.
Director of rugby Rob Baxter believes there are exciting times ahead for Exeter Chiefs after he committed his future to the club.
Exeter Chiefs were made to work hard for their third European Champions Cup win in a row, with Rob Baxter relieved to get over the line.
Rob Baxter's Exeter Chiefs survived a late scare to defeat Sale Sharks and remain firmly on track for the Champions Cup quarter-finals.
Northampton Saints made it four wins from five to go top of the Premiership, while Exeter Chiefs thrashed Wasps.