Northampton Saints produced a shuddering physical performance to bounce back and defeat Leinster 18-9 in Dublin.
In a storyline reminiscent of when the English side were thrashed by Ulster last season before winning away at Ravenhill, Northampton stunned Irish opposition once again.
Saints arrived for a full-on battle and showed an intensity and physicality that ruffled Leinster's feathers.
The attacking performance of Leinster's backs at Franklin's Gardens, spearheaded by Brian O'Driscoll, had at times verged on an exhibition. This week O'Driscoll had nowhere to go against the raw power of Northampton's pack.
Dylan Hartley's mantra for the first 60 minutes was to take on Leinster at close-range when penalties presented themselves in the hosts 22, utilising the visitors' effective maul.
It was a bold tactic that did yield George North's opening try, but given the proximity of the scoreline the fact that Northampton ultimately turned down three shots at goal could have ultimately cost them. Hartley's switch from the heart to the head, with Myler's penalty in the 64th minute, was wise.
In an opening that was the reverse of last week's affair and at times reminiscent to the way Northampton started the 2011 Heineken Cup final, Saints simply shot out of the blocks eager to prove a point.
Rob Kearney's clinical block on the flying Tom Collins handed Saints an early penalty but rather than opt for the posts, Myler chipped into the corner. It paid off - North cannoning through to score having been switched to 13 before the kick-off after Dom Waldouck's late withdrawal.
Northampton's makeshift centre pairing of North and Luther Burrell left them with two almighty carriers in midfield, with Burrell's presence sucking in the Leinster defenders to allow North to crash over and giving Saints the perfect start.
Striking early handed Leinster the initiative in Round 3 but they had to respond to an early deficit this time round, Ian Madigan's penalty putting them on the board.
The home side though suffered from early jitters. Madigan hooked a kick out on the full, Kearney spilled a promising high ball. Leinster made no errors in the first half at Franklin's Gardens, but they spluttered here.
Playing with more fire in the belly, Saints' big runners - Lawes, Burrell, North and Tom Wood - ran faster and hit harder.
North was only denied a second score thanks to a fine tackle from Madigan one-on-one, the 21-year-old latching on to a loose pass that ended in a red-zone penalty and a second kick into the corner and then a third as Leinster were penalised. Their confidence was infectious.
Leinster though still had control in certain areas. Their defence held when pummelled, their scrum stayed on top until late in the second half - but the line-out came under enormous pressure from Lawes' unit.
Kearney's boot momentarily reigned supreme, zinging kicks into the corner to keep the Northampton surge at bay, but Leinster still trailed 7-3 with the clock winding down until half-time.
The execution from the three-time champions was miles off the heights they reached seven days ago, and it was fortunate that Myler's penalty attempt before the break sailed miles wide to the left.
A basic dropped ball from Dickson gave Leinster an attack right from the restart and they pounced - working the outstanding Northampton defence left and right until after 22 phases Madigan was forced to take three points and cut the gap to one.
Northampton continued to ride the emotion of the occasion by choosing the corner over the posts. There was a time with the score at 6-7 when those decision to sacrifice points were always going to come into question.
North showed skill as well as force when his subtle pass released Ken Pisi into open space, but the Samoan's final ball to Jamie Elliott fell behind when it needed to go to hand. There was a subtlety to North's delivery than his opposite man, O'Driscoll, would have been proud of.
Myler's first penalty, earned at the scrum, had the Saints ahead by four but Leinster were rising - Madigan adding his third penalty to make the gap a single point again.
The departure of Hartley, Manoa and Lawes suggested Northampton had run out of gas in the tank, but Myler was then handed a difficult penalty wide out on the right. It was hopelessly wide again, but O'Driscoll's clearance was no better.
Saints were handed a penalty in an identical position, but with the maul so indefensible all night Myler's kick floated into the corner.
It culminated with Kahn Fotuali'i's drop goal - a winning drop goal, to cap a brilliantly physical performance that confirmed Northampton's pack - absent last weekend - as one of the most imposing in Europe.
Elliott's breakway try, after Leinster had pounded away for 22 phases, was just the icing on the cake - denying Leinster a losing bonus point in the process.
Pens: Madigan 3
Tries: North, Elliott
Leinster: 15 Rob Kearney, 14 Dave Kearney, 13 Brian O'Driscoll, 12 Gordon D'Arcy, 11 Luke Fitzgerald, 10 Ian Madigan, 9 Eoin Reddan, 8 Jamie Heaslip (c), 7 Shane Jennings, 6 Rhys Ruddock, 5 Mike McCarthy, 4 Devin Toner, 3 Mike Ross, 2 Sean Cronin, 1 Jack McGrath.
Replacements: 16 Aaron Dundon, 17 Michael Bent, 18 Martin Moore, 19 Leo Cullen, 20 Kevin McLaughlin, 21 John Cooney, 22 Jimmy Gopperth, 23 Zane Kirchner.
Northampton Saints: 15 Ken Pisi, 14 Jamie Elliott, 13 Dom Waldouck, 12 Luther Burrell, 11 George North, 10 Stephen Myler, 9 Lee Diickson, 8 Samu Manoa, 7 Tom Wood, 6 Calum Clark, 5 Christian Day, 4 Courtney Lawes, 3 Salesi Ma'afu, 2 Dylan Hartley (capt), 1 Alex Waller.
Replacements: 16 Mike Haywood, 17 Ethan Waller, 18 Tom Mercey, 19 Sam Dickinson, 20 Phil Dowson, 21 Kahn Fotuali'i, 22 Glenn Dickson, 23 Tom Collins.
Referee: Jerome Garces (France)
Assistant referees: Sebastien Cloute, Thomas Charabas (both France)
TMO: Eric Gauzins (France)
by Ben Coles