Saints through despite heavy defeat
Northampton moved into the European Champions Cup quarter-finals at Franklin's Gardens - but their hopes of a home tie were destroyed by rampant French challengers Racing Metro.
Racing's stunning 32-8 bonus-point victory meant they won Pool Five, with shell-shocked Saints progressing as one of three best runners-up across five groups.
It proved to be a dismal day for Northampton as Racing wing Juan Imhoff scored two tries, with full-back Benjamin Lapeyre and Wales international centre Jamie Roberts also touching down.
Scrum-half Maxime Machenaud kicked 10 points via two penalties and two conversions, while fly-half Benjamin Dambielle also added a conversion.
It was Saints' heaviest defeat of the season - Wales wing George North's seventh try of the European campaign and a Stephen Myler penalty provided no consolation - and Northampton also had their captain Dylan Hartley sin-binned and saw England flanker Tom Wood limp off.
Wood's departure early in the second period will have given cause for concern to watching England coaches Andy Farrell and Graham Rowntree, with his exit coming less than two weeks before the RBS 6 Nations opener against Wales in Cardiff.
And the collective damage suffered by Northampton was extensive, with an away quarter-final confirmed in early April, possibly against European champions Toulon.
Saints went into the pool finale without injured full-back Ben Foden (knee) and Courtney Lawes (ankle), but props Alex Corbisiero and Salesi Ma'afu were recalled to a team containing six members of England head coach Stuart Lancaster's Six Nations training squad.
Racing, meanwhile, included former Northampton forwards Brian Mujati and Juandre Kruger among their replacements, but Roberts and his fellow Wales Test player Luke Charteris both started in a side skippered by hooker Dimitri Szarzewski.
Pool Two results earlier in the day meant Saints and Racing had both secured quarter-final places before kick-off, but a home tie remained the considerable prize.
The teams engaged in some heavyweight sparring during the opening 10 minutes, with a missed Myler penalty the only scoring opportunity, but Saints were soon reduced to 14 players when Hartley was sin-binned.
The England hooker, who has recently completed a three-week ban - the latest suspension during a career littered with disciplinary issues - incurred referee Nigel Owens' wrath when he tackled a player while in an offside position on the floor at a ruck.
Machenaud kicked the resulting penalty, and then slotted another three points with Hartley still off the field after Saints were punished for collapsing a scrum.
It represented a sloppy start by the reigning Aviva Premiership champions and current league leaders, with Racing good value for their six-point advantage.
Myler opened Northampton's account through a 23rd-minute penalty, before Saints went desperately close to an opening try after slick handling behind the scrum saw North kick into space, but none of the advancing Saints players could take advantage.
Northampton were often forced into defensive mode for lengthy periods, with an outstanding Roberts making a number of powerful midfield thrusts, and Racing's patience was rewarded when they conjured a try during first-half stoppage time.
Backs and forwards handled impressively as they went through the phases, and lock Francois van der Merwe delivered a scoring pass to Imhoff, who had a simple task to touch down after Saints ran out of defensive numbers.
Machenaud's conversion attempt hit the post, but Racing were still good value for their 11-3 interval advantage.
Northampton needed a strong start to the second period, and wing Ken Pisi tore Racing's defence to shreds through a searing break, but Szarzewski's crunching tackle on George Pisi created a counter-attacking opportunity.
And Racing capitalised on it brilliantly, kicking possession to halfway before Imhoff showed Myler a clean pair of heels by sprinting away to score.
Machenaud added the conversion, but matters deteriorated for Saints when Racing posted a third try in less than five minutes either side of half-time after Wood departed.
On this occasion, Lapeyre's steepling kick was gathered by Northampton centre Luther Burrell, but Lapeyre merely ripped possession off him and went over unopposed for a try that Machenaud again converted.
North then went over to give Saints a glimmer of hope after Lee Dickson's break helped set him free but the conversion was missed.
Lapeyre turned villain when he was guilty of a deliberate knock-on near his own line, and Owens brandished a yellow card, sending Racing down to 14 men approaching the hour-mark.
But the victory had already been secured in emphatic fashion, and Roberts' 61st-minute score added icing to the cake, with Racing marching on as top seeds in the quarter-finals and Saints doing nothing more than limping through.