An experimental Leinster side conceded seven tries and failed to score as Northampton Saints ran riot in scorching conditions at Franklin's Gardens yesterday.
Joe Schmidt's side held solid for the opening quarter, but the concession of three tries before the break and a further four in the closing 13 minutes will frustrate the coach, who handed first starts of the season to Leo Cullen, Richardt Strauss, Isaac Boss and Devin Toner.
After a battle in the trenches in the opening 20 minutes, the home side made their first inroads 23 minutes in when Dom Walduck was on hand to barge across the line, despite the efforts of Andrew Boyle, who was forced off injured as a result.
Six minutes later, the Leinster line was breached once again, this time left winger Paul Diggin did the damage, and once again Ryan Lamb failed with the difficult conversion as the Saints led 10-0.
And just before half-time a nightmare half was capped for Leinster when the home side hit them for a third time. Former Blackrock College and UCD flyer Vasily Artemyev put the finishing touches on a slick move for Saints and Lamb's first success from the tee gave them a 17-0 lead at half-time.
Luther Burrell was yellow carded for a dangerous tackle on Jordan Coghlan a minute after the restart, but the Saints held solid in the face of some ensuing Leinster pressure.
And 12 minutes from the final whistle Scott Armstrong crashed over for the Saints' fourth try of the game, which was quickly followed by three more from Tom Wood, Tom May and Noah Cato in a thoroughly miserable day for Leinster.
Northampton Saints: B Foden; V Artemyev, G Pisi, D Walduck, P Diggin; R Lamb, L Dickson; S Tonga'iuha, D Hartley, B Mujati; M Sorenson, C Day; S Manoa, T Harrison, P Dowson. Reps: S Armstrong, L Burrell, N Cato, P Doran-Jones, M Haywood, T Hicks, M Hopley, T May, R McMillan, T Mercey, S Myler, B Nutley, R Oakley, K Pisi, M Roberts, A Waller, J Wilson, T Wood.
Leinster: A Conway; A Boyle, B Macken, J Coghlan, S Coghlan-Murray; N Reid, I Boss; J McGrath, R Strauss, M Moore; L Cullen, D Toner; D Ryan, J Murphy, L Auva'a. Reps: T Sexton, H van der Merwe, J Hagan, T Denton, B Marshall, J Cooney, I Madigan, C O'Shea, F Carr, J O'Connell.
Referee: W Barnes (RFU)