Five-time French champions Biarritz moved out of the Top 14 relegation zone on Friday with a 15-6 win at Agen.
It was a second successive win for the two-time European Cup runners-up to follow last weekend's 25-6 triumph over Toulon and once again it was the reliable boot of Dimitri Yachvili which proved key.
The halfback, who kicked 17 points against Toulon, added another 12 on Friday with Argentinian fly-half Marcelo Bosch adding three points with a drop goal.
Victory lifted Biarritz to third from bottom of the table with Lyon now propping up the league.
"We needed this success to back-up our win over Toulon and confirm our form," said Biarritz prop Sylvain Marconnet.
"It's all smiles in the dressing room. We'll savour this win and we continue with this spirit then we will be on our way. Of that, I'm absolutely certain."