Bath 11 Biarritz 12: Bath's Heineken Cup hopes suffered an immediate setback as Biarritz marksman Dimitri Yachvili punished their indiscipline at the Recreation Ground.
The France international scrum-half kicked four penalties to wipe out Bath's early 8-0 lead and clinch a potentially priceless pool 4 away win.
Bath exited at the group stage of last season's blue riband European tournament, and they are already battling to avoid a repeat despite starting promisingly through skipper Michael Claassens' try and an Olly Barkley penalty.
But Biarritz, Ulster’s next opponents, ground Bath into submission and left Yachvili to do the rest, with his clinching penalty struck immediately after Bath prop David Wilson was sin-binned 10 minutes from time.
Bath had chances to give Barkley a late drop-goal chance, but they proved tactically naive under pressure and Biarritz possessed the nous to close out a disappointing game.
Only four players — Ronan |O'Gara, Stephen Jones, Diego Dominguez and David Humphreys — have scored more points than Yachvili in Heineken Cup history.
Bath head coach Steve Meehan had warned his players during the build-up of Yachvili's danger, and Meehan's fears were realised as Biarritz took early charge of a group which also includes new Italian side Aironi.
Bath went into battle without England captain Lewis Moody, who suffered an eye injury during the Aviva Premiership home defeat against Gloucester last week, so fit-again Scotland international Simon Taylor moved into the back-row alongside Andy Beattie and skipper Luke Watson.
Prop Nathan Catt, 21, also made the staring line-up, while Biarritz included former Bath back Iain Balshaw, ex-Sale flanker Magnus Lund and his brother Erik, who was with Leeds last season, at lock.
Bath were determined to make amends for a feeble showing in the 18-3 loss to Gloucester, and they came out firing, leaving Biarritz floundering through an early Claassens try, but it was to be a false dawn for the English.