Loose kicking from both sides eventually results in a Leinster scrum just outside their own 22. The scrappy start is an obvious indication of the magnitude of this game.
The Leinster scrum is immediately under pressure which leads to a Jamie Heaslip knock on. Scrum to Northampton in a dangerous position.
Northampton can't take advantage of the position but a powerful clearance kick from Jonathan Sexton goes too far and results in another scrum.
Northampton's scrummaging is overwhelming the Leinster pack and after gaining a penalty advantage, the english side score the opening try with strong running on the blindside. Northampton 5-0 Leinster.
Myler slots a very difficult conversion. Northampton 7-0 Leinster.
Leinster's tackling to this point has been poor with Gordon D'Arcy in particular struggling to match up to his opposition. It was an initially break in his lane that led to Northampton into the Leinster 22.
Leinster reply well with a Shane Horgan claim that allows the team to batter its way into the Northampton 22. A knock on eventually gives Leinster a scrum in a good attacking position.
Leinster's scrum is under serious pressure before Gordon D'Arcy continues his poor start to the game with a knock on in a good position.
A good Leinster scrum is negated before Jamie Heaslip forces a turnover from his opposite number Roger Wilson. An infraction in a ruck leads to a Leinster penalty at the Northampton 10 meter line.
Jonathan Sexton struck the penalty with conviction to make the score Northampton 7-3 Leinster.
A poor clearance from Eoin Reddan surrenders possession inside the Leinster 22. Leinster are let off the hook by a reckless Dylan Hartley dive into the ruck. Leinster clear their lines with the penalty.
Northampton have obviously come into this game looking to play the percentages as they are happy to surrender possession to play in the Leinster half. There has been little back-line running in their game-plan in favor of direct running from their forwards.
Leinster are being dominated in the scrum. Another penalty is won at midfield for Northampton when Mike Ross is penalized. It is well within Stephen Myler's range.
Myler has the distance and direction which makes the score Northampton 10-3 Leinster.
Horgan once again gives Leinster an attacking base from the resultant kickoff. Another error however leads to a hacked clearance resulting in a lineout at midfield.
Leinster win clean ball and manage to work a way through the pressure defense from Northampton as Shane Horgan makes the first break before popping the ball to Sean O'Brien who fed Brian O'Driscoll. O'Driscoll was held up short of the line and became isolated which led to a scrum close to the Northampton try line.
O'Driscoll didn't look uncomfortable running but one must wonder if a 100% center would have made it all the way.
Northampton destroyed the Leinster pack again in the scrum affording them a penalty with the chance to clear their lines.
The ball found its way to the Leinster 22 btu Isa Nacewa decided to run it out rather than kick the ball clear. Nacewa fed Ken McLoughlin in space before the ball didn't go to hand. However Cian Healy had been held off the ball which led to a penalty and sin binning for a Northampton front rower.
Calum Clark had to be sacrificed by Northampton when a forward pass resulted in a Northampton scrum in Northampton territory.
The 7 men of Northampton destroyed the 8 of Leinster driving them back ten to fifteen yards to win a penalty. This can't continue if Leinster are going to win this game.
A huge kick from Myler moved Northampton into the Leinster 22.
Northampton's physicality was much greater with ball in hand which made them a threat to Leinster's goal line even with one less men. Good pressure from Luke Fitzgerald forced a forward pass to give Leinster a scrum in their own 22.
Once again the scrum was a problem. Northampton won the ball against the head and dragged the defense from side to side before cutting up the middle and darting over in the corner. Northampton 15-3 Leinster.
Ben Foden's try was a direct result of Leinster's failures in the scrum. This was looking like the Leinster team of old as their talent was being overran by the set piece problems. Northampton didn't slow down even with 14 men on the field.
Myler was machine like with his goal kicking. Northampton 17-3 Leinster.
Scrappy play resulted in two offenses from Northampton before Leinster eventually got a penalty at midfield in a good position to kick at goal.
On a positive note for Leinster, Sexton was striking the ball with conviction which was keeping them within touch. Northampton 17-6 Leinster.
Leinster's 8th handling error surrendered the ball to Northampton before their 9th gave them a scrum in front of goal.
Northampton returned to 15 men on the field.
Leinster's scrum finally showed some backbone but the backline was decimated on this occasion. Leinster's defense was stretched from sideline to sideline before Dylan Hartley drove over from a yard out for Northampton's third try of the first half. Northampton 22-6 Leinster.
Myler struck the post from a difficult angle.
Halftime: Northampton 22-6 Leinster.
Shane Jennings replaces Kevin McLoughlin.
Leinster kick off the second half with a mountain to climb.
Leinster get an early turnover in the first ruck which gives Sean O'Brien his first carry of the game unbelievably. Leinster sustain pressure through more than ten phases before Isa Nacewa breaks the line and brings them to the Northampton line.
Northampton's defense stiffens however and a turnover allows them to clear their lines.
Leinster started the second half with greater purpose and Northampton looked tired already. A Brian O'Driscoll break fed Jamie Heaslip who was held up short of the line once again but this time Leinster spread the ball wide and Jonathan Sexton arced to the corner beating Tonga'uiha to the try line. Northampton 22-11 Leinster.
Leinster's luck looked to be turning as Sexton's conversion bounced off the inside of the far post. Northampton 22-13 Leinster.
Leinster knocked the ball on once again but as a result of aggressive running rather than a mistake. Their tails were definitely up as Northampton gained no advantage in the scrum. The ball was moved sideways before a quick turnover was tapped by Reddan and Leinster attacked from deep.
Northampton were rattled now as they committed a cynical penalty at midfield that was lucky to not be more.
Leinster went down the line and secured the lineout. Sean O'Brien stood at first receiver once again to give the team an attacking base. Leinster's pack were taking their toll on the Northampton defence as they penetrated their way to the Northampton goal line.
Northampton were now scrambling once again as Gordon D'Arcy went over the line but was held up to give the attacking team a scrum five yards out.
The scrum was right next to the sideline giving Leinster a huge openside and no blindside.
Northampton showed strength in defense forcing Leinster to run through phase after phase before Jonathan Sexton showed great perseverance to get his second try of the game. Northampton 22-18 Leinster.
Sexton converted his own try. Northampton 22-20 Leinster.
Northampton were rattled. Ben Foden knocked a cleared kick forward under no pressure just inside his own half.
A telling scrum from the Leinster pack dominated their counterparts and forced a penalty giving Sexton a chance to add to his man of the match campaign. Sexton duly obliged. Northampton 22-23 Leinster.
Leinster have their first lead of the game with twenty minutes to go.
Leinster confidently secure possession and Sexton brilliantly clears the ball into Northampton's half.
Northampton's forwards weren't getting the forward momentum from the lineout like they had in the first half which forced the to kick the ball high. Nacewa plucked the ball from the air with ease before Cian Healy carried leading to Sean O'Brien carrying at least three defenders with him to the Northampton 22.
Another penalty committed by Northampton's Phil Dowson prevented a Leinster try but resulted in a second sin binning for the culprit. Jonathan Sexton chose to kick at goal from directly in front of the posts.
Sexton easily converted the penalty to make it Northampton 22-26 Leinster.
Sexton's growth into prominence in the game was reflective of the whole of the Leinster team as they were noticeably the better team.
Leinster were taking control of the game now and easily made their way to the Northampton 22 once again.
Leinster were camped on the goalline with a huge openside to attack through but they didn't need to use it as Nathan Hines burst through the heart of the Northampton defense to score another try. Northampton 22-31 Leinster.
Sexton converted a difficult conversion to make it Northampton 22-33 Leinster.
Northampton made multiple changes including the enigmatic Kieran Geraghty but Leinster forced another turnover that led to another shot at goal for Sexton from just inside the Leinster half.
The changes came too late as Northampton looked to have accepted their fate.
Sexton pushed the penalty wide which kept the score within two scores.
Leinster destroyed a Northampton scrum in the opposing half but Ben Foden and Chris Ashton burst into the Leinster 22 from their own half. A great recovery tackle from Isa Nacewa led to a turnover in Leinster's favor before they cleared the ball to the half way line.
Sean O'Brien's stature in the second half was huge for Leinster. He didn't feature at all in the second half but Northampton couldn't contain him in the tight at this point. Even as they looked to make a comeback, O'Brien single handedly blew up a ruck at midfield to win another penalty for his side.
Northampton were trying to press but repeatedly turned the ball over whenever they moved into the Leinster half. Leinster were resting on their laurels now but it didn't look like it was going to cost them.
Richardt Strauss won a Northampton line out which allowed Leinster to relieve even more pressure pitting Northampton deep.
A series of knock ons from both sides eventually led to a Leinster scrum on the Northampton 10 meter line.
Leinster empty the bench to a resounding ovation from the crowd.
Northampton look to run the ball from deep but it's all too predictable for Leinster who squash their attempts at attacking.
Full time: Northampton 22-33 Leinster.
Leinster's comeback is one of the most startling in the history of the competition. Their second half performance was worthy of winning any title.
IC Man of the Match:
Jonathan Sexton was a cut above throughout this game. Once his forwards gave him the chance to play he took over and was the difference between the teams.