Leinster survived an astonishing seven minutes of injury time to end Northampton's defence of the Heineken Cup.

The Irish provincial side had two players sin-binned, prop Gary Halpin and centre Shane Horgan, as they desperately defended their own line, and were fortunate not to concede a penalty try.

It was a game Northampton had to win if they had any chance of making the quarter-finals of the Heineken Cup they won last May.

Northampton coach John Steele was dejected after the loss: "We dominated territory and possession but Leinster pounced on their chances."

England scrum half Matt Dawson, making his return to rugby after a shoulder injury, was disappointed that Saints were not in a position to defend their title.

"I am disappointed because we are out of Europe. But I will reflect on it and by Monday I will be thinking we have got another game away against Leinster on Friday to start getting things right for the next stage in the season, which will be two games in the Tetley's Bitter Cup."

Leinster coach Matt Williams was not getting carried away withb the win: "We are going to enjoy today learn from it but next week is going to be crucial if we can win that we should be top of the group."

Leinster hit back with a brilliant 33rd minute try from winger Dennis Hickie, created with a piece of magic from Ireland centre Brian O'Driscoll.

Leinster edged clear on the stroke of half-time with a penalty from full-back Girvan Dempsey, who took over the kicking role from fly-half Eddie Hekenui who had missed three kicks at goal.

Leinster came out for the second half with all guns firing and scrum-half Brian O'Meara dropped a goal to leave the Saints trailing 5-11.

The European champions failed to cash in when flanker Trevor Brennan was yellow carded for a professional foul.

Hekenui's 66th minute penalty gave Leinster breathing space and they held on to ruin Northampton's hopes of making the play-offs.