Glasgow Warriors (12) 18
Pens: Parks 5 Drop: Parks
Biarritz Olympique (12) 22
Try: Lund Con: Yashvili Pen: Yashvili 3 Drops: Traille, Bosch
Biarritz took advantage of Glasgow fragility at the line-outs
Magnus Lund's second-half try proved to be the difference between the sides as Biarritz opened their Heineken Cup campaign with a win in Glasgow.
The boot of Dan Parks - one drop-goal and five penalties, one from his own half - had kept the home side ahead for most of the Pool Two match at Firhill.
But Lund beat Colin Gregor to the line to put Biarritz ahead after the break.
Marcelo Bosch and Damien Traille scored drop-goals, while Dimitri Yachvili's boot accounted for the other points.
Glasgow, who claimed a losing bonus point, had dominated the early possession and the pressure told as they won three early penalties.
Parks took advantage by slotting the ball over after four, eight and 15 minutes.
But Biarritz replied with their first serious incursion into the Warriors half, Yachvili slotting over the 17th-minute penalty.
The deficit was further reduced four minutes later when pressure from the French side gave Traille plenty of time to find his spot with a drop-goal.
Parks, though, restored Glasgow's advantage with an amazing kick from inside his own half, finding the target from fully 57 metres after 26 minutes.
Yachvili replied two minutes later from a difficult angle of his own before Parks blotted his copybook when he appeared to panic with Glasgow threatening the Biarritz line and opted for a drop-goal attempt that was well wide of target.
That proved costly for the home side shortly before half-time as another foray into Glasgow territory allowed Bosch an easy drop-goal chance to tie the scores at half-time.
Parks scored with a monster kick from his own half at Firhill
Glasgow were back in front immediately on the restart, with Parks scoring from in front of the posts.
Traille missed a drop-goal while Yachvili was off target with a penalty as Biarritz squandered opportunities to make some pressure tell.
However, a loose line-out from Glasgow allowed the visitors to score the only try in the 48th minute.
Following consultation with the video referee, it was decided that Lund had put pressure on the ball ahead of Colin Gregor.
Yachvili's conversion put Biarritz four points ahead and the French were now in the ascendancy.
Suddenly, though, it was Glasgow's turn to apply some pressure and Parks missed a long penalty before eventually reducing the deficit to a point with a drop-goal.
Some sloppy Warriors play allowed Yachvili another chance with a kick wide on the touchline that he converted to put the French four points ahead once more.
Glasgow had two thirds of the possession, but Parks again squandered some pressure on the French line with a kick over the defence that was swept up in front of the posts and Biarritz withstood all that the Warriors could throw at them in the closing minutes.
Glasgow Warriors coach Sean Lineen:
"We lost it. We were not out-played. They didn't win it.
"And we lost it thanks to the lineout and the baffling thing is that has been the one consistently strong area of our game all season.
"It has all come down to that one lineout in our 22 that we didn't control. It's going to haunt us.
"The boys never stopped and played great rugby at times.
"They just couldn't break that very very strong defence."
Biarritz co-coach John Isaac:
"We're very happy with that win. I feel this could be a key match in what looks to be a tight group.
"When we were in the same pool a couple of seasons ago, we lost here.
"Glasgow have a good set of backs and very mobile forwards and are by no means out of a pool that will spring surprises.
"We asked the boys to tighten set-piece in the second half and that became the key to the match.
"There might be some doubt about the try, but not in Magnus' mind; he says he clearly had control ahead of the Glasgow defender."
Glasgow: Stortoni, van der Merwe, McCall, Dewey, T. Evans, Parks, Gregor, Welsh, Hall, Low, Barker, Kellock, Vernon, Barclay, Beattie.
Replacements: McMillan for Stortoni (67), O'Hare for van der Merwe (41), Horne for Dewey (72), Tkachuk for Welsh (51), McArthur for Hall (51), Kalman for Low (77), Turner for Barker (56), Brown for Vernon (61).
Biarritz: Bosch, Ngwenya, Erinle, Traille, Brusque, Peyrelongue, Yachvili, Coetzee, Terrain, Johnstone, Thion, Taele-Pvihi, Lund, Harinordoquy, Faure.
Replacements: Tranier for Erinle (72), Barcella for Coetzee (41), August for Terrain (41), Carizza for Taele-Pvihi (62), Lauret for Faure (65). Not Used: Moala, Lesgourguex, Courrent.
Ref: Wayne Barnes (RFU).