Biarritz claimed a bonus-point 26-19 win over Bath to secure top spot in Heineken Cup Pool Four at the expense of Ulster.
The win sees the French giants claim a home quarter-final while Bath bow out of European action.
With Biarritz and Ulster level on 17 points each at the start of the final round of action, Bath knew they would have to claim a bonus-point victory to secure an unlikely route to the quarter-finals.
But they came up against a fired-up Biarritz outfit who were fighting for their own European fate.
And they got off to a flying start with a Dimitri Yachvili try after five minutes before Iain Balshaw grabbed tries either side of half-time.
Stuart Hooper handed Bath a glimmer of hope but it was short-lived with Takudzwa Ngwenya racing clear for the bonus-point try after 63 minutes.
Tom Biggs struck with two tries for Bath in the last 10 minutes but it was not enough as Biarritz marched into the knockout stages.