Lonodn Wasps were forced to overturn a half-time deficit to beat Bayonne 26-10 in Thursday's Challenge Cup clash at Adams Park.
After conceding an early try and trailing at 10-6 the break, Wasps produced a powerful second-half performance to leave them at the top of pool 4, after the first two rounds.
In the process, they denied Basque club a bonus point, which could prove crucial, come January, when the quarter-final places are decided.
Dai Young's team posted 20 unanswered points in the second half with Andy Goode kicking a total of 16 points on the night.
South African centre Sam Gerber gave Bayonne an early lead with a try which was converted by Stephen Brett after just four minutes.
Goode kicked three penalties to keep the hosts in touch before Ed Jackson put Wasps ahead with a try in the 51st minute.
Josh Bassett sealed victory with Wasps' second try, after good work by Christian Wade, before Goode kicked another penalty.
Bayonne have now gone11 games without victory against English sides.
Tries: Jackson, Bassett
Cons: Goode 2
Pens: Goode 3
Yellow cards: Bernad, Boutaty
London Wasps: 15 Tommy Bell, 14 Christian Wade, 13 Chris Bell, 12 Charlie Hayter, 11 Josh Bassett, 10 Andy Goode, 9 Joe Simpson, 8 Nathan Hughes, 7 Guy Thompson, 6 Ed Jackson, 5 Kearnan Myall, 4 James Cannon, 3 Jake Cooper-Woolley, 2 Carlo Festuccia, 1 Matt Mullan
Replacements: 16 Neil Cochrane, 17 Simon McIntyre, 18 Taoine Vea, 19 Joe Launchbury, 20 James Haskell, 21 Charlie Davies, 22 Joe Carlisle, 23 Ben Jacobs
Bayonne: 15 Scott Spedding, 14 Sam Gerber, 13 Santiago Fernandez, 12 Matthieu Ugalde, 11 Bastien Fuster, 10 Stephen Brett, 9 Mathieu Belie, 8 Opeti Fonua, 7 Jean-Jo Marmouyet, 6 Jean Moribot, 5 Mark Chisolm (c), 4 Lisiate Fa'aose, 3 Gert Muller, 2 David Roumieu, 1 JC Van Rensburg.
Replacements: 16 Gregory Arganese, 17 Aretz Iguiniz, 18 Nemiah Tialata, 19 Dewald Senekal, 20 Guillaume Rouet, 21 Julien Puricelli, 22 Guillaume Bernad, 23 Abdellatif Boutaty,
Venue: Adams Park
Referee: Peter Fitzgibbon (Ireland)