Reigning champions Saracens put one foot in the Gallagher Premiership play-offs after Owen Farrell's late penalty sunk title rivals Bath 15-12 at the Recreation Ground.
Northampton marched to a 40-17 Premiership bonus-point win over 14-man Leicester as they reinforced their status as table toppers on derby day.
It's been eight years since the Premiership had more than three clubs make it to the Champions Cup quarter-finals, but there remain six in play this season.
The RFU has apologised for an officiating error after Harlequins held off a storming Bath comeback for a win that lifted them back into the Premiership play-off places.
All of the details from Saturday's three Gallagher Premiership matches as Northampton, Bristol and Saracens all won.
Bath passed the biggest test of their revival yet by toppling Top 14 leaders Racing 92 29-25 and qualifying for the Champions Cup knockouts in April.
Full-back Tom de Glanville scored two tries as Gallagher Premiership title contenders Bath returned to winning ways.
Bath missed the chance to top of the Premiership table as they crashed to a convincing 35-22 defeat to Leicester.