Northampton secured a place in next season's Heineken Cup after producing an astounding fight back against Memorial Stadium hosts Bristol.

The Saints were lamentable for 79 minutes of a forgettable contest ruined by the fussy refereeing of Wayne Barnes and a succession of injuries.

But the game was transformed in dramatic fashion after Bristol's substitute hooker Neil Clark was sin-binned.

Northampton trailed 16-0 but they scored three tries in eight minutes to complete an amazing success.

England hooker Steve Thompson, who appeared as a half-time substitute, crashed over on 79 minutes, then Scotland wing Sean Lamont sliced through a huge gap to take Northampton within reach of their opponents.

Bristol, whose forwards had dominated most of the match, dug deep to try to close the game out but England wing Ben Cohen touched down after 87 minutes to clinch the four points Northampton needed to guarantee Heineken Cup qualification before captain Bruce Reihana kicked his second conversion.

Northampton will join Sale Sharks, Leicester, Wasps, London Irish and Gloucester as the sixth Guinness Premiership representative in top-flight European competition next term.

For so much of the contest it looked as though Northampton would be left requiring a victory over Franklin Gardens visitors Sale next Saturday to realise their European ambition.

Yet Bristol folded spectacularly following Clark's dismissal after building up a healthy advantage through a first-half try by wing Marko Stanojevic and 11 points from the Premiership's top-scorer, fly-half Jason Strange.

Northampton lost eight of their opening 10 league games, but eight victories from the next 11 lifted them into the top six and will mean a Heineken Cup debut campaign next season for their superstar New Zealand fly-half Carlos Spencer.

Saints' late show signalled the end of Heineken Cup hopes for Saracens and Worcester, who would both have been still in the hunt had Bristol prevailed.

The first half was a totally forgettable affair as referee Barnes struggled to impose any authority on a match punctuated by hold-ups for minor injuries and several unforced errors.

Strange kicked Bristol into a 6-0 lead after 30 minutes, with Northampton repeatedly making errors behind the scrum, it was no surprise when the home side extended their lead just before the break.

Full-back Bernardo Scortoni had a try harshly disallowed when scrum-half Shaun Perry's pass to him was ruled forward, yet Bristol finally broke Northampton's resistance three minutes later.

A sustained spell of pressure from the home forwards meant Northampton finally ran out of defensive numbers and Strange sent Stanojevic for a try which the fly-half also converted.

Strange's third penalty after 45 minutes gave Northampton a mountain to climb, and their cause appeared a hopeless one nine minutes from time when flanker Sam Harding received a yellow card.

Down to 14 men, and 16 points adrift on the score board, Northampton could scarcely wait for the final whistle and Bristol coach Richard Hill rang the substitutions, including replacing his entire front-row of David Hilton, Mark Regan and Darren Crompton.

Even when Thompson scored wide out, the most ardent of Northampton's travelling fans were celebrating what they thought was merely a consolation try.

But their team scented an unlikely revival as they marched into Europe one week inside the distance.

Bristol, meanwhile, can reflect on a hugely satisfying first season back in the Premiership, but Hill could not disguise his frustration at the final whistle, describing the defeat as "leaving a bitter taste".

And there was also an injury worry for Bristol when scrum-half and England hopeful Terry suffered a hamstring problem and, although he played on for the entire game, he finished with his left leg heavily strapped.