Perpignan (20) 29
Tries: Penalty try, Marty Cons: Porical 2 Pens: Porical 5
Northampton (8) 13
Tries: Ashton, Mujati Pen: Geraghty
David Marty caused Northampton no shortage of problems
French champions Perpignan produced a dominant performance to claim their first Heineken Cup win of the season with victory over Northampton Saints.
The hosts raced 10-0 ahead before the Saints rallied, Chris Ashton reducing the deficit with a superb solo effort.
David Marty finished a fine move before half-time before Brian Mujati went over to keep the visitors in contention.
But the boot of Jerome Porical made the difference and the full-back landed 19 points to secure a deserved triumph.
It was vital result for Perpignan following their shock 9-8 defeat at Treviso in the opening round of matches last weekend.
They leapfrog Northampton to move top of Pool 1 but will be overtaken by either Munster or Treviso, who meet at Thomond Park on Saturday.
Fresh from their magnificent victory over Munster six days previously, the Saints arrived at Stade Aime Giral in high spirits.
But they knew it would take a monumental effort to upset a side who had not lost at home in Europe in their previous 14 matches and were unbeaten on their own turf this season.
The visitors were cheered on by a healthy travelling contingent but, after entering the field to a cacophony of boos from the raucous Catalan crowd, they started in timid fashion and were swiftly on the back foot.
Porical's majestic display started with a third-minute penalty and, after a fumble in front of the line by flanker Jean-Pierre Perez, he soon gave Perpignan a 10-point cushion following referee Nigel Owens' award of a penalty try as Northampton struggled to contain the hosts' scrum.
The opening exchanges had been scrappy but suddenly a half of fluent rugby was unfolding and, after Shane Geraghty and Porical exchanged penalties, the impressive Ashton struck with his third try in two games.
Fed by Ben Foden on the right wing, Ashton chipped over the Perpignan defence and, benefiting from a kind bounce, brushed aside scrum-half Nicolas Durand to touch down inches in front of the dead ball line.
Troubled by a swirling wind, Geraghty missed his difficult conversion chance to make the score 13-10 and, crucially, Perpignan would reassert their authority before the break.
The impressive Ashton went over for his third try in two games
They were routinely disrupting the Northampton set-piece, lineout and scrum and when fly-half Nicolas Laharrague's chip was collected by Maxime Mermoz, a well-timed offload enabled Marty to race under the posts.
Perpignan started the second half as they finished the first and at times their scintillating ability to keep the ball alive in phase after phase left their opponents chasing shadows.
One such attack should have been rewarded with a try, only for Henry Tuilagi's score in the corner to be disallowed because of a forward pass by Perez.
To their credit, the Saints responded by launching an attacking raid of their own and Foden jinked his way past several Perpignan players and surged deep into opposition territory.
Ashton provided support and set up a ruck, allowing Northampton to recycle, spread the play from left to right and send Mujati diving over the line.
Unfortunately for Jim Mallinder's men, the near-faultless Geraghty failed to convert and the momentum swayed back towards Perpignan.
Young lock Courtney Lawes conceded a needless penalty, which Porical made no mistake in dispatching, and two more gems from the 24-year-old's right boot ended any hopes Northampton harboured of an unlikely comeback.
Northampton coach Jim Mallinder:
"Perpignan are one of the best sides in Europe, particularly at home. You have got to play at your real best to win out here and we didn't do that. We didn't play to the best of our ability and deserved to come second.
"We scored two tries and showed that if we play to our best we can win at places like this. We'll look at the video on Monday and we'll see that there were also things we did wrong and we can correct those.
"They came at us hard, particularly in the scrum, but we kept going at that. We improved and probably got on top in the second half. At the breakdown we didn't get a lot of good ball. That was where the game was won by them.
"We were really disappointed to concede that try just before half-time. We also made a few mistakes, particularly under pressure.
"It was really frustrating and I thought at around 55 to 60 minutes we could get back into the game. We scored a good try and had quite a lot of possession."
Perpignan: Porical; Sid, Marty, Mermoz, Candelon; Laharrague, Durand; Freshwater, Guirado, Mas, Alvarez, Vilaceca, Britz, Perez, Tuilagi.
Replacements: Manas for Marty (73), Meyer for Laharrague (70), Cazenave for Durand (70), Schuster for Freshwater (53), Tonita for Guirado (59), Pulu for Mas (73), Tincu for Britz (61).
Not Used: Vivalda.
Northampton: Foden; Ashton, Clarke, Downey, Reihana; Geraghty, Dickson; Tonga'uiha, Hartley, S Gonzalez Bonorino, S. Gonzalez Bonorino, Lawes, Kruger, Dowson, Best, Wilson.
Replacements: Mayor for Clarke (58), Myler for Downey (65), Mujati for S. Gonzalez Bonorino (41), Mujati for S. Gonzalez Bonorino (41), Fernandez Lobbe for Lawes (69), Easter for Wilson (63).
Not Used: Sharman, Dreyer, Dickens.
Ref: Nigel Owens (WRFU).