Steve Diamond's Saracens, who rejoined Europe's elite after a five-year absence via the play-offs, not only held their own against one of the tournament favourites but positively put Biarritz to the sword.
Man of the match Glen Jackson finished with 14 points and created the first-half try for Ben Johnstone with a perfectly-executed off-load under the Biarritz posts.
The Saracens pack, having been tested early, assumed control as the game wore on and the 11,167 inside Vicarage Road knew it was to be their day when captain Hugh Vyvyan, a loose-forward by trade, landed a 40-metre drop goal.
Biarritz could not cope with the Saracens' intensity as Jackson dictated proceedings with a supreme tactical kicking display.
Not since 2000, when Saracens beat the mighty Toulouse home and away, have the supporters' fez been raised to acclaim such a European performance.
Saracens began brightly and led through Jackson's fourth-minute penalty when Biarritz, with a formidable pack featuring France internationals Thomas Lievremont, Imanol Harinordoquy and Jerome Thion, put the squeeze on.
Three times they rumbled towards the Saracens line but the defence held firm, twice heaving the French pack into touch, and when Biarritz executed an impressive drive from the lineout, Kyran Bracken got himself under the ball and denied blind-side flanker Thierry Dusautoir the score.
The resolute defence, epitomised by a crunching tackle from centre Kevin Sorrell on his opposite number Damien Traille, preserved Saracens' narrow 3-0 lead.
Jackson missed with a drop-goal attempt and then a second penalty shot before Saracens received a major let-off when Biarritz centre Frederico Martin Arramburu skipped a grubber kick into touch when a simple outside pass would almost certainly have created the opening score.
And Saracens ruthlessly took full advantage. Jackson's kicking game was in prime shape and twice he pressed Biarritz back onto their own try-line with raking cross-field touch-finders.
Biarritz hooker Benoit August was penalised for a crooked throw and from the five-metre scrum Bracken sent the ball wide left in search of an opening.
The chance eventually came back inside when Jackson created the space with a superb offload and Johnstone burst onto the ball and under the posts.
Traille, who had gone down injured in the build-up to the score, was replaced immediately and left the field nursing his arm that could render him doubtful for France's autumn Tests against Australia, Canada, Tonga and South Africa.
Biarritz launched one final attack before the interval but another crunching midfield tackle, this time from lock Simon Raiwalui, forced Arramburu to spill the ball and secured Saracens a 10-0 half-time lead.
If Biarritz had any hopes of making a quick start to the second half, Saracens dashed them with a rolling maul that powered on for fully 35 metres.
Biarritz, running out of numbers, eventually had to concede the penalty and although Jackson sent his kick across the posts, it was an emphatic statement of intent from Saracens.
Quickly they were back in Biarritz territory, on the back of another superb clearance from Jackson and then arrived the moment which confirmed this was to be Saracens' day.
Vyvyan, playing at blindside flanker, took the ball in midfield and launched a long-range drop goal that sailed between the posts and brought Vicarage Road to its feet.
Yachvili finally got Biarritz on the board with a 57th-minute penalty after Saracens had been caught offside.
But it did nothing to inspire a slipshod Biarritz side and Saracens simply came back stronger. Another monstrous drive from the forwards and a break from Jackson took them to within five metres of the line.
Biarritz were penalised for offside at the ruck and Jackson slotted his second penalty to put Saracens 16-3 ahead.
Biarritz could not relieve the pressure applied by Jackson's kicking game and he was on target again with five minutes remaining to put Saracens three scores clear when Denis Avril was caught off-side and sent packing to the sin-bin.
Biarritz eventually worked a breakthrough, with fly-half Julien Peyrelongue scoring in the last minute of injury time, but Jackson provided the coup de grace with another giant drop-goal.