Bath’s Heineken Cup hopes suffered an immediate setback as Biarritz marksman Dimitri Yachvili punished their indiscipline to help the French club claim a 12-11 victory 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 Four 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, beaten by Toulouse in the Heineken final last term, 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 that also includes Ulster and 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. Barkley had already opened Bath's account with a penalty, before his delicious off-load created space for Nick Abendanon and Matt Carraro to combine and send Claassens over.
Although Barkley's missed conversion attempt followed a misdirected first-minute penalty, they had made an immediate statement of intent and left their opponents needing to find a response.
Biarritz stirred towards the end of a lively opening quarter when centre Michael Bond gathered loose ball and stormed up field. A try seemed certain, given that American speed merchant Takudzwa Ngwenya was on Bond's shoulder for the pass, but Abendanon scythed down Ngwenya with a brilliant tackle before Bath won turnover ball and cleared possession to safety.
The Bath forwards, second-best against Gloucester and Northampton this term, established momentum through their hunger for the battle, with Catt leading a far more dynamic approach. Biarritz knew they were in a fierce physical battle, underlined when their back-row talisman Imanol Harinordoquy required lengthy treatment after attempting to halt another concerted Bath drive.
The visitors continued to concede regular penalties – Welsh referee James Jones readily punished their technical indiscipline – yet Bath still only trooped off at the interval eight points up.
Yachvili cut Biarritz's deficit through an early second-half penalty, and that looked the most likely way they would threaten Bath, given their paucity in attack.
A second Yachvili penalty made it 8-6, signalling a spell of concerted Biarritz pressure that almost resulted in a try. Number eight Raphael Lakafia grounded possession, but he was ruled to have made another movement after being tackled.
Yachvili though, soon completed his penalty hat-trick to put Biarritz ahead for the first time, and there was no sign of the visitors panicking, even when Barkley edged Bath back in front 12 minutes from time.
Wilson though, made their job easier when he was yellow-carded for a technical offence, leaving the home side a player down for the closing 10 minutes as Yachvili restored Biarritz's advantage. And the visitors then expertly kept possession, keeping Bath at a distance territorially, which merely underlined Bath's earlier reckless failure to manoeuvre a potential match-winning opportunity for Barkley.