Cardiff remain top of Pool Six in the Heineken Cup after a workmanlike 10-6 victory over Biarritz at Parc des Sports Aguilera.
Jamie Robinson scored the game's only try after 13 minutes as Cardiff produced a stern defensive display to clinch only their second win in France.
Biarritz hit back through penalties from Damien Traille and Julien Peyrelongue but the result stretched Cardiff's unbeaten run in the pool to four games and left them on the verge of qualification for the quarter-finals.
Ospreys claimed a second bonus-point victory in successive weeks to complete an Italian job over Treviso with a 36-16 win in Italy.
The Welsh region moved a point clear of Leicester at the top of Pool Three after a crucial triumph at the Stadio Comunale di Monigo.
Number eight Filo Tiatia grabbed the vital fourth try to add to those of Sonny Parker, Alun Wyn Jones and Jonathan Thomas.
Toulouse moved closer to a place in the quarter-finals with a 26-13 away win over Newport-Gwent Dragons.
Tries during the opening flurries of each half by wings Maxime Medard and Cedric Heymans emphasised a gulf in class, although Toulouse still had to dig deep.
Frederic Michalak kicked a drop-goal and two penalties that underlined early Toulouse dominance, while David Skrela converted Medard's fourth-minute touchdown, yet the Dragons gave it their best shot.
Prop Rhys Thomas scored a try six minutes before the break, with fly-half James Arlidge booting eight points, but Toulouse were always capable of moving up a gear when it mattered.