An injury-time penalty from Benjamin Boyet saw Bayonne grab the spoils in the Basque derby with a 16-15 win at Parc des Sports d'Aguilera on Sunday.
Despite being ahead for most of the contest, it looked like Bayonne were set to finish on the losing side when Julien Peyrelongue slotted a 77th minute penalty to make it 15-12 to BO.
But the visitors - missing scrum-half Mike Phillips and full-back Cedric Heymans through internal suspensions - managed to gain field position and when the home side offended, Boyet stepped up from 30 metres out to claim a much-needed win.
Christian Lanta's side were 10-6 to the good at half-time thanks to a try from Thibault Lacroix, which was converted by Boyet, before Cedric Garcia followed that with a penalty for an early lead. Those scores came either side of two kicks from home fly-half Jean Pascal Barraque.
Barraque cut the lead down to just one point eleven minutes after the break before Peyrelongue and Boyet battled it out with the boot.
And it was to be the latter's and Bayonne's day as they claimed four key league points.
Pen: Barraque 3, Peyrelongue 2
Pen: Garcia, Boyet 2
Biarritz: 15 Iain Balshaw, 14 Dane Haylett-Petty, 13 Charles Gimenez, 12 Damien Traille, 11 Aled Brew, 10 Jean Pascal Barraque, 9 Yann Lesgourgues, 8 Raphael Lakafia, 7 Thibault Dubarry, 6 Benoit Guyot, 5 Pelu Taele, 4 Erik Lund, 3 Ben Broster, 2 Arnaud Heguy, 1 Johannes Blaauw.
Replacements: 16 Jean Philippe Genevois, 17 Fabien Barcella, 18 Jerome Thion, 19 Magnus Lund, 20 Julien Peyrelongue, 21 Seremaia Nakala Burotu, 22 Takudzwa Ngwenya, 23 Francisco Gomez Kodela.
Bayonne: 15 Scott Spedding, 14 Joe Rokocoko, 13 Thibault Lacroix, 12 Manu Ahotaeiloa, 11 Marvin O'Connor, 10 Benjamin Boyet, 9 Cedric Garcia, 8 Julien Puricelli, 7 Jean Joseph Marmouyet, 6 Guillaume Bernad, 5 Mark Chisholm, 4 Dewald Senekal, 3 Nemiah Tialata, 2 David Roumieu, 1 Aretz Iguiniz.
Replacements: 16 Gregory Arganese, 17 Vitolio Manukula, 18 Abdellatif Boutaty, 19 Dwayne Haare, 20 Guillaume Rouet, 21 Matthieu Ugalde, 22 Sam Gerber, 23 Renaud Boyoud.