Saints were savaged by Clermont Auvergne as the French table-toppers proved far too powerful in the Challenge Cup curtain raiser at Franklin's Gardens.
Clermont ran in six tries on another sobering European afternoon for Saints, who had few answers to the strength of their visitors.
Chris Boyd's men were beaten 41-20 with their only tries coming from Tom Collins and David Ribbans very late on.
Clermont's strength up front laid the platform, with Saints overwhelmed in the scrum during the first period.
And after the break, the French side's backs displayed their flair, setting up opportunities for their forwards to flourish in acres of space.
Saints have now suffered five defeats in seven games in all competitions and will head to Newport next Friday aiming to kick-start their European campaign against the Dragons.
Boyd's men were hit with an early injury blow against Clermont as Harry Mallinder, who had started the game brightly, was involved in a huge early collision.
And after trying to battle on, the full-back was forced off with just five minutes played.
That meant a back line reshuffle for Saints, with Ahsee Tuala moving to full-back, Andrew Kellaway switching to the wing and Luther Burrell coming on at outside centre.
Saints had started well and had chances to kick early penalties, but they preferred to take their French opponents on up front.
And it almost paid dividends as a scrum set up a move from which Biggar put a grubber through, but Kellaway couldn't quite ground the ball under the attentions of Isaiah Toeava.
It wasn't long before Saints did take the lead as Clermont continued to infringe and Biggar landed the penalty from in front of the posts.
But Boyd's men had endured issues with restarts in previous matches, and those problems resurfaced as Clermont were presented with a penalty, which Greig Laidlaw kicked.
The French giants then started to assert their authority at scrum time, sending Saints into rapid reverse.
And after Kellaway couldn't collect a Biggar grubber close to halfway, full-back Toeva raced towards the line, with Lewis Ludlam and Tom Collins combining to bring down the big man.
But Saints could do nothing to stop Peter Betham not long after, as the former Leicester player breezed in on the wing after another dominant Clermont scrum.
Laidlaw missed the tricky touchline conversion and his team soon gave away a silly penalty for bad sportsmanship, with Biggar taking the three points to cut the gap to two.
But in a game saturated with scrums, Clermont continued to hold the upper hand and after Sitaleki Timani went off for a toilet break, his replacement, Peceli Yato, pushed his way over.
Laidlaw converted to make it 15-6 and it was to be 20-6 at half-time thanks to another fine flying finish from Betham.
And Clermont were first to register after the break, bagging their bonus point through a Rabah Slimani score from a sizeable shove from a lineout drive.
Laidlaw converted and it was starting to become a damage limitation job for the home side, who were seeing little of the ball.
Clermont were relentless in their pursuit of more tries, inflicting more pain on Saints with a fifth score, from lock Arthur Iturria.
Laidlaw again added the extras to make it 34-6 and only the voices of the few away fans could be heard at a silenced Gardens.
And it wasn't long before Yato struck again, with Clermont creating an abundance of free ground to finish another flowing move.
Laidlaw's conversion made it 41-6 and time seemed to be ticking far too slowly for Saints' liking.
But there was finally something for the home fans who had stuck it out to cheer as Clemont unusually spilled the ball and Collins showed his speed to race clear from his own half.
Grayson added the conversion and there was to be another try before the end as Piers Francis did superbly to inspire a break and Ribbans finished from close range.
Grayson again added the extras with the final kick of the game as Saints at least finished a tough afternoon with a flourish.
Saints: Mallinder (Burrell 5); Tuala, Kellaway, Francis, Collins; Biggar (Grayson 62), Reinach (Mitchell 53); Waller (cc) (van Wyk 62), Hartley (cc) (Haywood 58), Painter (Franks 53); Ribbans, Barrow (Moon 53); Haskell (Gibson 58), Ludlam, Harrison.
Clermont Auvergne: Toeava; Nanai Williams, Penaud, Lamerat (Naqalevu 58), Betham; Fernandez (Lopez 58), Laidlaw (Parra 69); Falgoux (Kakabadze 62), Kayser (Ulugia 47), Slimani (Zirakashvili 53); Timani, Vahaamahina (van der Merwe 29); Iturria, Cancoriet, Lee (c) (Yato 62).
Referee: Nigel Owens