Northampton fell short with a courageous second-half fightback as Leinster emerged 20-17 winners in their Investec Champions Cup semi-final at Croke Park.
The repeat of the 2011 final was a mismatch for the first hour with wing James Lowe running in a hat-trick against the Gallagher Premiership leaders, who suffered from a high error count.
A 82,300 capacity crowd in Dublin watched the first England club to play at the home of GAA fire few shots until George Hendy crossed to give them hope of an upset.
Northampton then began to look more like the daredevil side that has taken the Premiership by storm this season and, when Tom Seabrook touched down with six minutes remaining, they had Leinster on the ropes.
But the four-time champions clung on having already done enough to reach the final, where they will face Toulouse or Harlequins at Tottenham Hotspur Stadium on May 25th.
Perhaps in a sign of nerves, Saints started by giving the ball away cheaply and there was worse to come when a penalty close to their line saw Jamison Gibson-Park fling a long pass to Lowe, who cut inside to score.
And the early onslaught continued when Lowe strolled over for his second try after Gibson-Park flicked on a superb offload from the charging Caelan Doris.
There was no respite for the underdogs as they gave up penalty after penalty, one of them at a pulverised scrum and another for offside at the restart, and Ross Byrne was able to kick another three points.
Northampton’s attack ignited briefly, creating a half chance that vanished through poor timing, but a Fin Smith penalty at least got them off the mark.
Saints needed to score but instead Lowe completed his hat-trick after a marauding run from Ryan Baird put Leinster on the front foot.
Leinster’s ability to keep the ball alive depleted Northampton’s stock of defenders, giving Lowe another easy try.
Two Saints attacks in the 22 were foiled by penalties but eventually the pressure that was building on the home line told when Hendy’s chip and chase was spilt by Leinster and the wing seized the chance to touch down.
The second-half was proving far more of a contest and when Seabrook raced over with Smith converting, the result hung in the balance.
Leinster were paying the price for taking their foot off the visitors’ throat, but they had the smarts and resilience to close out the tense final few minutes.
