Northampton produced an error-strewn display before coming through their Heineken Cup opener against Castres 18-14 at Franklin's Gardens.
The 2000 champions were lacklustre in attack and lethargic in defence, but ensured their Pool One clash ended in victory thanks to tries either side of half-time from Bruce Reihana and Ben Foden.
Despite his try, New Zealander Reihana endured a night to forget, missing three penalty attempts and one conversion in the opening 40 minutes to keep Castres in with a shout.
The French visitors got on the board when forward Joe Tekori bundled over, however they too were guilty of missing numerous penalty kicks, but at least return home with one losing bonus point to their name.
Saints, as they so often do at Franklin's Gardens, came out all guns blazing in an attempt to catch their French visitors cold.
Castres repelled the early barrage well though, despite Courtney Lawes and Shane Geraghty both breaking the gain-line inside the opening five minutes.
The first penalty attempt at goal came 11 minutes in, however Reihana pulled his kick well wide and Castres were handed a reprieve.
Reihana and Pierre Bernard traded further missed chances midway through the half, however Castres were improving as the match developed and it came as no surprise when they snatched the lead.
A powerful scrum from the French outfit put Saints on the back foot and lock Tekori picked up the pieces before outmuscling Lee Dickson to touch down.
Bernard missed the ensuing conversion as the kicking woes for both teams continued.
Reihana then missed penalty kick number three from straight under the posts, the Saints fans not afraid to let their feelings heard despite the New Zealander's legendary status at the club.
But on 32 minutes the Saints spectators were all smiles, Reihana making amends for his inept kicking display with a simple try in the corner. The veteran winger missed the resulting conversion - bringing an end to his place-kicking duties for the evening.
Castres edged back ahead two minutes later through CJ McIntyre's drop-goal, however their cause was not helped when hooker Mathieu Bonello was sent to the sin-bin for cynically killing the ball.
Northampton were handed a chance to level the scores on the stroke of half-time, however Geraghty's attempt bounced three times before reaching the posts.
But within 35 seconds of the restart memories of that miss were dispelled, Foden collecting a neat inside pass from Phil Dowson to burst clear and touch down under the posts. Geraghty's conversion through the middle brought about the loudest cheer of the night.
Bernard squandered another kickable opportunity minutes later, and French frustrations increased when the referee wrongly disallowed a Castres try when adjudging a knock-on against a French player when in fact Foden got the touch.
Bernard scored his first penalty from four attempts to reduce the deficit to 12-11, however Geraghty responded in kind to extend the lead back to four.
Another Bernard attempt fell short, however with nine minutes remaining the Northampton nerves were jangling again when the Castres full-back found his range.
At 15-14 the match was perfectly poised heading into the closing stages, but Northampton looked the more assured at the death and Stephen Myler sealed the win with a late penalty.
Tries: Reihana, Foden
Pens: Geraghty, Myler
Pens: Bernard 2
Northampton: 15 Ben Foden, 14 Chris Ashton, 13 Jon Clarke, 12 James Downey, 11 Bruce Reihana, 10 Shane Geraghty, 9 Lee Dickson, 8 Roger Wilson, 7 Tom Wood, 6 Phil Dowson, 5 Christian Day, 4 Courtney Lawes, 3 Brian Mujati, 2 Dylan Hartley (c), 1 Soane Tonga'uiha.
Replacements: 16 Brett Sharman, 17 Regardt Dreyer, 18 Euan Murray, 19 Calum Clark, 20 Mark Easter, 21 Ryan Powell, 22 Stephen Myler, 23 Joe Ansbro.
Castres: 15 Pierre Bernard, 14 Romain Martial, 13 Pierre-Manuel Garcia, 12 Romain Cabannes, 11 Vincent Inigo, 10 Cameron McIntyre, 9 SÃ©bastien Tillous-Borde, 8 Chris Masoe, 7 Yannick Caballero, 6 Ibrahim Diarra, 5 Joe Tekori, 4 Scott Murray, 3 Daniel Saayman, 2 Mathieu Bonello, 1 Yannick Forestier.
Replacements: 16 Benjamin Kayser, 17 MichaÃ«l Coetzee, 18 Anton Peikrishvili, 19 Matthias Rolland, 20 Jannie Bornman, 21 Thomas Sanchou, 22 Seremaia Bai, 23 Marc Andreu.
Referee: John Lacey