Northampton Saints left it very late to seal a 13-3 Heineken Cup victory over Castres at Franklin's Gardens on Friday.
Saints kept their slim hopes of a place in the last eight alive with a scrappy win, but it went down to the wire as the scores were level with five minutes to play.
Saints are now certain of a place in the knockout stages of the Amlin Challenge Cup but must hope results elsewhere go their way to maintain their interest in Europe's premier event.
Whatever happens they will have to improve on their performance against Castres, which fell well below their usual standards.
Saints were completely dominant at scrum-time but offered little else on a subdued night at Franklin's Gardens.
The back three combination of the Pisi brothers - George and Ken - and new full-back Fa'atoina Autagavaia had a game to forget and that conspired against Saints getting into any sort of attacking rhythm.
Luther Burrell, too, would have struggled to get in the England squad had he displayed such erratic form earlier in the season.
Castres' fast line speed in defence also played its part in keeping Saints restricted to three points before the break from the boot of Stephen Myler right on the stroke of half-time.
French champions Castres thought they had scored the first try of the game on 37 minutes from a quickly taken line-out, but referee Alain Rolland had spotted that Remi Lamerat had used a different ball.
Replacement scrum-half Rory Kockott won a penalty just inside the Saints half shortly after arriving on the pitch and kicked the resulting penalty to bring the sides on level terms with 52 minutes on the clock.
Poorly executed passes continued to blight Saints, much to the frustration of the 12,000+ crowd, and it took a penalty from Myler for the home side to regain the lead with four minutes left.
George Pisi sealed victory when he charged down Kockott's kick to score the only try of the game with the last play. Myler's conversion brought an end to a forgettable encounter.
Try: G. Pisi
Pens: Myler 2
Northampton Saints: 15 Fa'atoina Autagavaia, 14 Jamie Elliott, 13 George Pisi, 12 Luther Burrell, 11 George North, 10 Steve Myler, 9 Lee Dickson, 8 Samu Manoa, 7 Tom Wood, 6 Calum Clark, 5 Christian Day, 4 Courtney Lawes, 3 Salesi Ma'afu, 2 Dylan Hartley (c), 1 Alex Waller.
Replacements: 16 Mikey Haywood, 17 Ethan Waller, 18 Gareth Denman, 19 Sam Dickinson, 20 Phil Dowson, 21 Kahn Fotuali'i, 22 Glenn Dickson, 23 Ken Pisi.
Castres: 15 Brice Dulin, 14 Marcel Garvey, 13 Romain Cabannes (c), 12 Remi Lamerat, 11 Remi Grosso, 10 Daniel Kirkpatrick, 9 Julien Tomas, 8 Piula Faasalele, 7 Jannie Bornman, 6 Mathieu Babillot, 5 Richie Gray, 4 Christophe Samson, 3 Anton Peikrishvili, 2 Marc-Antoine Rallier, 1 Yannick Forestier.
Replacements: 16 Saimone Taumoepeau, 17 Antonie Claassen, 18 Mihaita Lazar, 19 Benjamin Desroche, 20 Yannick Caballero, 21 Rory Kockott, 22 Paul Bonnefond, 23 Pierre-Gilles Lakafia.
Venue: Franklin's Gardens
Referee: Alain Rolland (Ire)
Assistant referees: David Wilkinson, Michael Black (both Ire)
TMO: Simon McDowell (Ire)