Saracens saw their Heineken Cup quarter-final hopes destroyed in ruthless fashion as French championship leaders Biarritz powered into the knockout stages at Parc des Sports Aguilera.

Biarritz, beaten semi-finalists during the last two European campaigns, sent Saracens packing to guarantee a home tie which they intend playing across the nearby Spanish border in San Sebastien.

Saracens provided brave and committed opposition, yet the Biarritz backs mercilessly unlocked their defence through tries for centre Federico Martin-Arramburu, wing Jean-Baptiste Gobelet, centre Philippe Bidabe, full-back Nicolas Brusque and fly-half Julien Peyrelongue, while hooker Benoit August also touched down.

Scrum-half Dimitri Yachvili slotted four conversions and a penalty, with replacement Julien Dupuy also landing a conversion.

Saracens conjured a quality try for prop Kevin Yates, allied to eight points from Glen Jackson's boot, yet they were outclassed and outpaced, conceding 24 unanswered second-half points.

Lock Simon Raiwalui and substitute Dan Scarbrough compounded the problems by collecting yellow cards for reckless tackles, with Saracens' season now moving rapidly towards anonymity, despite finishing second in Pool Four.

Rugby director Steve Diamond faces a tough job lifting Saracens for their 10 remaining league games, but Heineken Cup qualification through the Guinness Premiership is now an essential requirement or the club's millionaire owner Nigel Wray could lose patience.

Biarritz though, are major contenders for European rugby's ultimate club prize, a fact that will not be lost on the likes of rivals and fellow qualifiers Toulouse or Leicester.

Saracens went into their biggest match of the season following a wretched Premiership run that saw them suffer four successive defeats, while Biarritz boasted an unbeaten home Heineken Cup record stretching back more than four years.

Diamond named first-team regulars Kevin Sorrell, Alan Dickens and Scarbrough on the bench, with captain Hugh Vyvyan lining up at lock rather than his more familiar position of number eight.

Biarritz paraded an enviable array of internationals, with French back-row star Serge Betsen continuing his recovery from a fractured cheekbone among the substitutes, going on 17 minutes from time.

Saracens, 22-10 conquerors of their hosts at Vicarage Road three months ago, were stretched by an early Yachvili break, but the visitors settled encouragingly as Kris Chesney stole a Biarritz lineout before Jackson landed a superb 48-metre penalty after seven minutes.

Biarritz looked to spin possession wide at every opportunity, embracing the need for a winning bonus point, and their adventure was rewarded with an opening try for Martin-Arramburu when he stepped his way inside a static Saracens defence.

Yachvili converted, and although he then drifted a 40m penalty wide, alarm signals were sounding for Saracens as they found themselves pinned inside their own 22.

And Jackson deepened the crisis, rifling an attempted defensive clearance straight to Biarritz wing Sereli Bobo, whose powerful run set up an imposing attacking platform and Arramburu expertly freed Gobelet for a try.

Saracens appeared in deep trouble, but they produced a majestic response when Jackson scythed through a midfield gap, found his half-back partner Moses Rauluni in support before flanker Ben Russell sent Yates powering over to give Biarritz a piercing wake-up call.

Jackson converted to make it 12-10, but Saracens then suffered a major injury blow when centre Thomas Castaignede limped off and was replaced by Sorrell with 16 minutes of the first-half remaining.

Saracens mounted a brave rearguard action as the Biarritz pack adopted a juggernaut approach, but such power inevitably buckled the Premiership club just before half-time when Yachvili put August scampering across.

Yachvili added the extras, and despite a second successful Jackson penalty, Saracens ended a lively opening period reduced to 14 men when Raiwalui was sin-binned for a high tackle on his opposite number Jerome Thion.

Yachvili continued his patchy kicking form though, sending the resulting penalty wide, and Saracens were still in contention, 19-13 adrift at half-time.

Thion, who required prolonged treatment after being pole-axed by Raiwalui's challenge, did not reappear for the second period and was replaced by Olivier Olibeau.

But Biarritz were not remotely ruffled, and they claimed a priceless fourth try within 80 seconds of the restart as slick work by the backs was rounded off by Brusque in such nonchalant fashion to suggest Saracens were in for a prolonged defensive exercise.

Yachvili booted the conversion and then added a penalty as Biarritz scored 10 unanswered points during Raiwalui's 10-minute absence, and it was one-way traffic after that with Saracens wilting against a side superior in all departments.