Saracens turned up the heat to melt Racing Metro's European ambitions with a 19-14 victory in heavy snow outside Paris on Friday.
In apocalyptically cold conditions, Sarries produced a storming first half that proved enough for victory despite a spirited comeback from the French hosts in the second period.
Saracens led 16-0 at half-time but Racing scored two tries soon after the break to set up a nail-biting finish for those who could actually see the action through the blankets on snow coming down from the night sky.
19-year-old fly-half Owen Farrell shined again for Saracens, kicking two penalties, a drop goal and a conversion while also setting up a try for Brad Barritt.
There were doubts whether the game would go ahead but the ground staff were able to make the pitch just about playable at the Stade Olympique Yves du Manoir.
There were three late changes to the Racing team after number eight SÃ©bastien Chabal, lock Jone Qovu and centre Henry Chavancy were forced to withdraw after stomach bug ripped through the home changing room.
Whether the rest of the team were affected is not yet clear but they certainly did not match the visitors for intensity as Saracens hustled, bustled and out-chased the Parisians to every loose ball in the opening 40 minutes.
Saracens were full-value for their 16-point half-time advantage against a disorganised Racing side that at times seemed more interested in getting into the warm changing rooms than getting stuck into their opponents.
The visitors were plying the pressure immediately from kick-off and soon had a 6-0 lead thanks to Farrell's first penalty and a clever drop goal.
The lead could have been a lot more but David Strettle just clipped the touch line on his way to the corner. The TMO inexplicable called for a 22 restart rather than a line-out - with Brendan Venter no doubt doing his best to bite his tongue.
The visitors were rewarded for their efforts just before the break however when centre Barritt - the man who gave away Racing's first try last week - found his way over the line with a strong run.
Farrell's conversion and another penalty just before the hooter allowed the English club to head for a warm drink with a healthy lead.
The second half was almost the complete opposite as Racing came out of the sheds charged up and Mirco Bergamasco charged down Neil de Kock to pounce for his team's first try shortly after the restart.
From being down and out at the break, the hosts were right back in the game with half-an-hour left when the Racing scrum won a penalty and scrum-half Nicolas Durand took a quick tap to sneak over.
Jonathan Wisniewski's second conversion set up a grandstand finish as the teams headed into the final quarter separated by just two points.
The French side had the bit between their teeth but were unable to bridge the gap and Farrell's last-minute penalty wrapped up the win, though his side remain rooted to the bottom of the standings.
Man of the match: Hats off to the Sarries line-out that hardly faltered for 80- minutes, but we'll back up the official choice of Owen Farrell, who made all the right decisions at all the right times.
For Racing Metro:
Tries: Bergamasco, Durand
Cons: Wisniewski 2
Pens: Farrell 3
Racing-Metro: 15 Juan Martin Hernandez, 14 Sireli Bobo, 13 Mirco Bergamasco, 12 FranÃ§ois Steyn, 11 Benjamin Fall, 10 Jonathan Wisniewski, 9 Nicolas Durand, 8 Jacques Cronje, 7 Alvaro Galindo, 6 John Leo'o, 5 Karim Ghezal , 4 Santiago Dellape, 3 Juan Pablo Orlandi, 2 Carlo Festuccia, 1 Julien Brugnaut.
Replacements: 16 Benjamin Noirot, 17 Andrea Lo Cicero, 18 Benjamin Sa, 19 Lionel Nallet , 20 Jerome Fillol, 21 Dan Scarbrough, 22 Remi Vaquiin, 23 Bernard Le Roux.
Saracens: 15 Chris Wyles, 14 David Strettle, 13 Michael Tagicakibau, 12 Brad Barritt, 11 James Short, 10 Owen Farrell, 9 Neil de Kock, 8 Kelly Brown, 7 Jacques Burger, 6 Justin Melck, 5 Hugh Vyvyan, 4 Hayden Smith, 3 Petrus du Plessis, 2 Schalk Brits, 1 Rhys Gill.
Replacements: 16 Jamie George, 17 Deon Carstens, 18 Carlos Nieto, 19 George Kruis, 20 Ernst Joubert, 21 Richard Wigglesworth, 22 Nils Mordt, 23 Noah Cato.
Venue: Stade Olympique Yves du Manoir
Referee: George Clancy (Ireland)
Assistant referees: Paul Haycock (Ireland), Mark Hermin (Ireland)
Television match officials: Peter Ferguson (Ireland)