Northampton Saints were brought back down to earth after they suffered a 50-28 loss away to Champions Cup holders Bordeaux in a repeat of last season's final.
Bath lost a 26-point lead in an epic south-west derby only to snatch back victory in the most dramatic fashion in the closing seconds to beat Exeter 33-26, before Northampton Saints returned to the top of the Prem table.
Sale emphatically ended a run of four straight Prem Rugby defeats by thumping fellow strugglers Harlequins 43-17 in a bonus-point win at the CorpAcq Stadium in Salford.
Munster bounced back from a disappointing defeat to Bath last week to comprehensively beat Gloucester 31-3 in the Champions Cup at Páirc Uí Chaoimh in Cork.
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.
Gloucester beat Harlequins 26-15 at Kingsholm to record their first Prem win of the season at the sixth attempt.
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.
Marcus Smith's return inspired Harlequins to their first win of the Prem season as Saracens saw their perfect start come to an end with a 20-14 loss at The Stoop.