Saints were punished for failing to turn possession into points as they suffered a 24-7 defeat to Clermont Auvergne at a typically raucous Stade Marcel Michelin.
Jim Mallinder's men dominated the territory for long spells, but they only had a Christian Day try and Harry Mallinder conversion to show for their efforts.
Clermont, who lost fly-half Camille Lopez to a broken leg during the first half, were ruthless in their execution as they took the chances that came their way, scoring four tries.
And that meant Saints did not get any points as a reward for their sizeable show of character, which came six days after a record home European defeat to Saracens.
The game included a showing from referee Ben Whitehouse that left many scratching their heads as the Welshman attracted the ire of both teams.
He dished out three yellow cards on the day, with Dylan Hartley and Kieran Brookes sin binned for Saints and Rabah Slimani punished for Clermont.
And Saints were the ones who suffered most as they eventually found themselves on the end of a second defeat in as many Champions Cup matches this season.
The men in lime green had been forced to work hard defensively from the off with only a superb last-ditch tackle from Teimana Harrison stopping centre Remi Lamerat from scoring.
But it wasn't long before Clermont registered as the hosts cranked up the heat in the scrum, pushing Saints back over their own line and allowing No.8 Fritz Lee to dot down.
Morgan Parra converted, but Saints responded well, with Harry Mallinder leading a break that eventually saw Clermont forced to hold out on their own line.
There was then a lengthy stoppage as Clermont No.10 Lopez suffered a broken leg, bringing a spell of silence to the atmospheric ground for the first time.
Lopez was stretchered off, with everyone in the stadium, including the Saints players applauding him.
When the game resumed, Saints thought they had scored as Hartley pounced on a loose ball close to the Clermont line.
But he was denied the try by the TMO, who felt there had been a knock-on in the build-up, and the near misses continued as Ben Foden was stopped agonisingly short by Lamerat.
Saints' frustration was accentuated by the sin binning of Hartley as Whitehouse felt the Saints hooker had swung an arm into the face of Sitaleki Timani while attempting to clear out at a ruck.
Total confusion then broke out as the performance of official Whitehouse continued to attract attention.
With Mike Haywood forced off with a head injury and Hartley in the sin bin, the referee tried to action a scrum with Saints only having two front row forwards on the pitch.
Eventually, after a lengthy spell of bamboozlement and amid loud booing from the home fans, Kieran Brookes was allowed to come on and the uncontested scrum took place.
Clermont managed to find some space at the end of what seemed like the half that would never end, and Charlie Cassang, who had replaced Lopez, went in under the posts.
Parra converted with the final kick of the half to give his side a 14-0 lead that was harsh on Saints, who had spent the majority of the 40 minutes in opposition territory.
And the harsh deficit was to get harsher just after half-time as Cassang claimed a high ball and raced away to register his second score of the match.
Parra missed the conversion, but the lead was now 19 points and Saints were going to have to show real spirit to avoid suffering a second heavy defeat in succession.
And they did display the necessary desire as after winning a penalty, they kicked to the corner and drove Clermont over with Day the man grabbing the score.
Mallinder converted to cut the gap to 12 points and Saints were refusing to relent, going close to adding a second try, with only a last-gasp tackle stopping them from scoring in the corner.
Clermont were being stretched all over the field, but they defended stoically to stop Saints getting any more hope.
And the away side were hit by another yellow card as prop Brookes was penalised at the scrum.
But the numbers were evened up almost immediately as Clermont prop Slimani was sin binned for a shoulder charge on Hartley.
Saints were not able to take their chances though, and Clermont were ruthless.
The home side scored their bonus point try thanks to a show of power from prop Etienne Falgoux, putting the game beyond Mallinder's men.
Clermont Auvergne: Toeva; Abendanon, Penaud, Lamerat, Raka; Lopez (Cassang 22), Parra (c); Chaume, Kayser, Slimani; van der Merwe (Jedrasiak 50), Timani; Cancoriet, Lee, Lapandry.
Saints: Mallinder; Foden, Tuitavake (Stephenson 67), Burrell (Pisi 67), Collins; Francis, Groom (Reinach 61); Waller (van Wyk 67), Hartley (c) (Haywood 67), Ford-Robinson (Brookes 40); Ratuniyarawa (Paterson 61), Day (Gibson 61); Lawes, Wood, Harrison.
Referee: Ben Whitehouse (Wales)