Taku Ngwenya's sensational solo try helped Biarritz to a Heineken Cup victory over Saracens.
After a scoreless first half, the visitors took the lead through Owen Farrell's penalty.
But after Imanol Harinordoquy's try and a Julien Peyrelongue penalty gave the hosts the advantage, Ngwenya picked the ball up deep inside his own half and danced through the Saracens defence.
Alex Goode's late score earned Sarries a losing bonus point.
It was no more than Saracens deserved for their efforts at the death, which also saw James Short held up when over the line.
Biarritz, though, inspired by Harinordoquy, had already done enough to earn the victory that gives the top of Pool Five a congested look.
After two rounds, Saracens and Ospreys, who drew 26-26 with Treviso, have six points, with Biarritz a point behind.
Farrell and Marcelo Bosch had chances to give their sides the lead in an attritional first half, but both men were off target with place kicks.
Only when Farrell eventually broke the deadlock early in the second period did the match come to life, with the home side responding with a brilliant try.
Former England international Iain Balshaw launched a daring counter-attack from his own line and, following good interplay from the Biarritz pack down the left flank, Dane Haylett-Petty fired a perfectly weighted kick to the corner for man-of-the-match Harinordoquy to score.
Peyrelongue's penalty extended the advantage before Ngwenya's scintillating score took the French side to the verge of victory.
On the counter-attack, the United States international cut through the English champions to score under the posts.
Short appeared to give Sarries hope, but his score was chalked off by the video referee, leaving Goode to salvage some solace by squeezing in at the corner.
Biarritz: Balshaw, Traille, Baby, Ngwenya, Haylett-Petty, Bosch, Roussarie, Barcella, Marconnet, August, Thion, E. Lund, Harinordoquy, Guyot, Lakafia.
Replacements: Peyrelongue for Baby (52), Bolakoro for Bosch (75), Watremez for Barcella (75), Heguy for August (73), Taele-Pvihi for Harinordoquy (77), Faure for Lakafia (75).Not Used: Gomez Kodela, Lesgourgues.
Saracens: Wyles, Strettle, Farrell, B. Barritt, Short, Hodgson, Spencer, Gill, Smit, Stevens, Borthwick, Smith, Brown, Burger, Joubert.
Replacements: Powell for Strettle (69), Goode for Hodgson (42), Carstens for Gill (70), Botha for Smith (48), Saull for Burger (13).Not Used: George, Nieto, Baldwin.
Referee: Nigel Owens (Wales).