Paris - Racing Metro clinched a dogged 15-3 win over Edinburgh on Friday to keep their European Cup quarter-final hopes alive as last season's semi-finalists slumped to a fourth successive defeat.
In a battle of the boot at Murrayfield, Olly Barkley and Gaeton Germain kicked penalties inside the first seven minutes with Piers Francis cutting the French side's lead after 27 minutes.
But the former Waikato Chiefs fly-half was guilty of five misses out of six attempts on a rain-swept night while Germain was successful with three second half penalties.
The win took Racing to the top of Pool 1 ahead of Sunday's match between Saracens and Munster.
Torrential rain reduced the Stade Aguilera pitch in Biarritz to swimming pool conditions as the French side set about avenging their shock 22-14 defeat to Connacht in Ireland last weekend.
Dmitri Yachvili kicked a third-minute penalty before his team had a try ruled out when Takudzwa Ngwenya aquaplaned into touch before he was able to ground the ball.
However, Biarritz grabbed a deserved lead on the half hour when Iain Balshaw darted between a gap left wide open by Connacht fly-half Dan Parks to score with Yachvili succeeding with a tricky conversion from the touchline for a 10-0 lead at the interval.
The pitch got increasingly heavier in the second half ruining the game as a spectacle.
Fijian replacement Seremaia Burotu grabbed a last-minute try, converted by Yachvili, to give Biarritz a 17-0 victory.
But Biarritz remain five points behind Pool 3 leaders Harlequins who are at home to Zebre on Saturday.
Biarritz went into the game having suspended coaches Serge Milhas and Jack Isaac from their posts till January 6.
The duo were replaced in the interim by two emblematic figures at the club, manager Laurent Rodriguez - who was joint coach when Biarritz won the 2002 French title - and youth academy director Mathieu Rourre.
"They were appalling conditions," said Rourre. "But I am happy for the club and the spirit. We wanted to return to simple things and values and we showed that."
Fourth-round results in the European Cup on Friday (kick-offs):
Edinburgh (SCO) 3 Racing Metro (FRA) 15
Biarritz (FRA) 17 Connacht (IRL) 0
Ospreys (WAL) v Toulouse (FRA) (15:35)
Treviso (ITA) v Leicester (ENG) (15:35)
Harlequins (ENG) v Zebre (ITA) (17:00)
Ulster (IRL) v Northampton (ENG) (20:00)
Exeter (ENG) v Scarlets (WAL) (17;40)
Leinster (IRL) v Clermont (FRA) (17:40)
Montpellier (FRA) v Cardiff Blues (WAL) (20:00)
Saracens (ENG) v Munster (IRL) (17:00)
Castres (FRA) v Glasgow (SCO) (14:45)
Toulon (FRA) v Sale (ENG) (17:00)