All four Pro14 sides in European Rugby Champions Cup action on Saturday secured victories, three coming against French opposition.
Three weeks before the start of the Six Nations, Sam Underhill has been ruled out of the tournament in a significant blow to England.
Bath finished the game with 11 men as they suffered defeat to lowly Worcester Warriors in the 98th minute.
England's Sam Underhill will undergo a specialist review after suffering ankle ligament damage and could miss the start of the Six Nations.
Bristol Bears ended 2018 with a huge win over Newcastle Falcons, while Bath moved up to fifth with victory over Leicester Tigers.
Bath are into the Premiership's top six after beating Wasps, while Gloucester won at Newcastle Falcons.
Saracens battled past Cardiff Blues to stay top of Pool 3, while Toulouse came out on top in an entertaining clash with Wasps.
A low-scoring draw at Bath was enough to lift Sale Sharks back off the bottom of the table, although they were frustrated after leading.
There were Premiership wins for Newcastle Falcons and Worcester Warriors on Friday, with the former moving off the foot of the table.
Teenage lock Joel Kpoku came off the bench to give Saracens a seventh Premiership wins out of seven, which put them back at the summit.