Superb Blues make hay in gardens
Northampton 10 Leinster 37
Leinster took command of the 'Pool of Death' with a five-try, five-star performance to take away all the points from Northampton last night.
They arrived in the East Midlands without a win from their last seven away matches in the Champions Cup.
That didn't bode well for their latest crusade at Franklin's Gardens, a place they lavished with their skills three years ago.
They couldn't have been more impressive from the start, going through multiple phases for Rob Kearney to slice through and Garry Ringrose was on his shoulder to collect and touch down. Isa Nacewa's conversion made it 7-0 in just the third minute.
The Blues scrum was completely dominant in crushing out a penalty for Nacewa to make it a 10-point game in the 11th minute.
Then, the maul went for 20 metres and European debutant Adam Byrne's incision almost created an opening for Robbie Henshaw.
Sadly, Leinster lost Joey Carbery to an ankle injury to hand Ross Byrne his European debut, which was quickly followed by Northampton's opening points, a Stephen Myler penalty in the 20th minute.
Soon afterwards, there was also the worrying sight of the ball twice bouncing before being claimed by Kearney.
The Saints then survived a 20-phase attack from Leinster and a Sean O'Brien try attempt was ruled out for a knock-on as the first-half came to a close.
Leinster restarted the second period like they did the first, by keeping the ball until Nacewa tickled a kick deep into enemy territory.
Immediately, Kearney was pulled from the action which led to the introduction of Rory O'Loughlin, becoming the third Leinster debutant.
McGrath spilled the ball at the rear of a maul to cough up an ideal scrum position for the home side.
Then, the scrum-half was bumped off by JJ Hanrahan and, when the recycle came, Hanrahan whipped away a wide ball for replacement Ahsee Tuala to ground a try, Myler's extras levelling it up in the 47th minute.
Leinster needed a response and they got it from Nacewa's penalty wide on the left.
When Leinster infringed at a ruck, Northampton looked to their lineout only for hooker Mike Heywood to be loose with the ball.
This signalled the entrance of England captain Dylan Hartley to thunderous applause.
Leinster's reaction was to carry the fight forward for a stunning scrum penalty.
They moved away smoothly only for Adam Byrne to lose the ball forward from Nacewa's accurate dispatch.
This was repaired when the front row destroyed Northampton for yet another penalty.
It was Leinster's turn to refuse three points in favour of a lineout-into-maul.
McGrath made the initial snipe. O'Brien took it on and Jamie Heaslip and Devin Toner latched on to drive home the try for Nacewa's conversion, making it double scores (20-10) in the 57th minute.
The game was far from gone.
It was then Hartley chose the moment for a brainless swinging forearm into the head of O'Brien, a blatant red card if ever there was one.
It meant O'Brien left the field for a head injury assessment and Jack Conan was given an opportunity to make an impact.
Luke McGrath's quick reactions made mud out of another compromised scrum and Josh van der Flier was then the spark for major ground gained.
The lineout was gathered and the ball put into the hands of fly-half Byrne.
His beautifully weighted cross-field ball was taken brilliantly overhead by O'Loughlin for 25-10 in the 66th minute.
This was the moment when the Saints were limited to playing for pride and Leinster for the bonus point.
They just seemed to lose their composure, kicking the ball away three times, instead of holding on against the 14 men.
It all came down to the speed and footwork of Jamison Gibson-Park for the fourth try in the 75th minute ahead of Nacewa's final five.
The three-time winners are now six points clear of French clubs Castres and Montpellier, who play tomorrow.