Biarritz came back from being 12-0 down to beat Treviso 29-12 and claim a bonus point to keep their Heineken Cup hopes alive on Friday.
The Basques took revenge for last weekend's defeat in Italy but were looking shaky at half time.
Kris Burton scored two early penalties before flanker Francesco Minto was sent-off for the visitors in the 25th minute.
Burton continued to take his opportunities but the hosts fought back in the second half. Tries by Iain Balshaw, Dane Haylett-Petty, Wenceslas Lauret and Arnaud Heguy completed the comeback and a crucial bonus-point victory.
Having succumbed to a surprise 30-26 defeat to Treviso last week, struggling Biarritz undid their good work of overcoming Saracens in week one.
It was the visitors who garnered control of the match in the initial stages, and Burton opened the scoring with a penalty after five minutes.
Soon after, the fly-half added another three-pointer before Minto was red carded for a headbutt on Yann Lescourgues.
However, the hosts were unable to take advantage in the first period with Burton once again proving decisive with the boot, kicking two penalties in quick succession to extend their lead to 12-0.
Julien Peyrelongue eventually got the French side on the scoreboard three minutes before the break with a three-pointer of his own.
But the hosts upped the intensity in the second half and scored two quick tries to change the tide.
Firstly, former England international Balshaw went over which was then followed by a Heylett-Petty touchdown.
Peyrelongue converted the first of the two opportunities and the hosts led for the first time. And two late tries from Lauret and Heguy sealed the five-point win.
Tries: Balshaw, Haylett-Petty, Lauret, Heguy
Cons: Peyrelongue 3
Pens: Burton 4
Red card: Minto (Treviso - 25th minute)
Biarritz Olympique: 15 Iain Balshaw, 14 Taku Ngwenya, 13 Marcelo Bosch, 12 Damien Traille, 11 Ilikena Bolakoro, 10 Julien Peyrelongue, 9 Yann Lesgourgues, 8 Imanol Harinordoquy, 7 Wenceslas Lauret, 6 Benoit Guyot, 5 Pelu Taele, 4 Manuel Carizza, 3 Francisco Gomez Kodela, 2 Arnaud Heguy, 1 Yvan Watremez.
Replacements: 16 Benoit August, 17 Sylvain Marconnet, 18 Thomas Lebrequier, 19 Jérôme Thion, 20 Jean-Baptiste Roidot, 21 Florian Faure, 22 Benoît Baby, 23 Dane Haylett-Petty,
Benetton Treviso:15 Luke McLean, 14 Ludovico Nitoglia, 13 Alberto Sgarbi, 12 Andrea Pratichetti, 11 Tommaso Benvenuti, 10 Kristopher Burton, 9 Tobias Botes, 8 Robert Barbieri, 7 Alessandro Zanni, 6 Francesco Minto, 5 Cornelius van Zyl, 4 Antonio Pavanello, 3 Lorenzo Cittadini, 2 Enrico Ceccato, 1 Michele Rizzo.
Replacements: 16 Diego Vidal, 17 Ignacio Fernandez Rouyet, 18 Pedro di Santo, 19 Benjamin Vermaak , 20 Gonzalo Padrò, 21 Marco Filippucci, 22 Willem de Waal, 23 Edoardo Gori,
Venue: Parc des Sports Aguilera, Biarritz
Referee: Peter Fitzgibbon