Two-time European winners Munster were dumped out of the Champions Cup at the pool stage for just the fourth time since 1998 as they were stunned by Castres at Thomond Park 31-29.
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 are into the Challenge Cup final for a fifth time after beating Italian team Benetton 40-23 at Kingsholm.
Leicester Tigers claimed a second Champions Cup win from as many rounds, beating Clermont, while Saracens dug deep to win at Lyon.
Leicester booked a mouth-watering Heineken Champions Cup quarter-final with Leinster after completing the job against Clermont with a 27-17 win.
Leicester claimed their first win at Stade Marcel-Michelin in 17 years as they beat Clermont Auvergne 29-10 in Heineken Champions Cup round of 16.
Ulster secure their place as one of the top seeds in the Champions Cup knockouts courtesy of an exciting 34-31 bonus-point win vs Clermont.