Biarritz wrestled control of Pool 4 in the Heineken Cup but only after surviving a genuine scare from Ulster at Parc des Sports Aguilera in a game that finished 33-19 to the hosts.
The French champions looked to have the game in the bag after just 13 minutes when they scored three tries, two by Philippe Bidabe and prop Petru Balan.
But tries either side of half-time by Neil and Simon Best set up a thrilling climax as Ulster threatened to pull off a major surprise in the south of France.
However Biarritz, one of the favourites for the Heineken Cup this season having lost in the semi-finals for the last two years, secured the victory when wing Jean-Baptiste Gobolet charged over seven minutes from time.
Ulster had lost their last six games away from home in Europe while Biarritz had only lost once on home soil in five years of Heineken Cup action.
And the game had looked well beyond Ulster after just 13 minutes by which time they had conceded three tries, the first within 70 seconds of the kick-off.
Biarritz's pack surged forward, Kevin Maggs let Federico Martin Aramburu out of his grasp before releasing Philippe Bidabe for a clear sprint for the corner. Three minutes later and Romanian prop Petru Balan burrowed his way over from close range in the same corner after Biarritz's outstanding back-row combined in open play.
Bidabe then grabbed a second after chipping ahead and beating Kieran Campbell in a race for the ball.
Ulster finally found their feet and dragged themselves back into the match through reliable sources.
Neil Best scored after two attempts at a driving lineout had been held up short on the Biarritz line. Then Humphreys did the rest with two penalties to leave them trailing 20-11 at the break.
That was reduced even further when brother Simon Best was adjudged to have grounded the ball from another lineout drive. That was just rewarded for the captain who had asked Humphreys to kick a penalty into the corner rather than at the posts.
Dimitri Yachvili edged the home side seven points ahead with another penalty but Ulster were still in line for a bonus point, as well as a potential victory, until Gobolet picked up a bouncing ball to surge through to score.
Julien Peyrelongue then added a drop goal in the closing stages to seal victory.
