Munster just keep on giving to this competition. They completed their pool stages with six wins for the first time and did it with a devastating second-half display to secure a home quarter-final in April.
Their form up to now may have been suspect and last night their scrum took a hammering, but they stayed in the game and then cut loose with a lethal edge not seen up to now this season. Simon Zebo stole the honours with a hat-trick and Ronan O'Gara missed just one in a 26-point haul as they marched into the quarter-finals with intent. It was no surprise that Northampton came at Munster from the outset but it was clear from the early stages that the Saints had the squeeze on the visitors' scrum.
That led to all sorts of difficulties for Tony McGahan's men during a lively opening half, with Northampton striking a huge psychological advantage after 15 minutes with a penalty try from a five-metre scrum.
Ryan Lamb added the conversion to make it 13-3, with Lamb landing penalties after five and twelve minutes to emphasise their dominance.
But Munster, with Peter O'Mahony superb at openside and Donnacha Ryan also impressive, fought back and O'Gara reduced the deficit at the end of the opening quarter with his second penalty. O'Gara reduced the deficit further after 29 minutes as another penalty opportunity arose after Munster kept it simple and went through the phases.
Lamb responded with a good drop-goal but Northampton flanker Phil Dowson made a mess of O'Gara's superb restart, with Zebo pouncing to give Munster go-forward ball which finished with BJ Botha squeezing over. O'Gara added the extras to level and then pushed Munster in front for the first time with another penalty just before the break.
Northampton responded and Lamb left them level at 19-19 at the interval when he made no mistake with a penalty.
Munster exploded into action straight after the restart, pinning Northampton back before they went wide and Johne Murphy did superbly to get the touchdown in the right corner with one hand, with O'Gara adding the points.
There was even better to come with a fleeting move wide to the left by O'Gara, Keith Earls and Murphy putting Zebo through for an excellent score to open up a 31-19 lead.
But Northampton hit back and while Murphy and Conor Murray did well to dispossess Soane Tonga'uiha over the line, Munster did not clear the danger and Saints used their best weapon -- the scrum -- to score another penalty try, with a dust-up resulting in the scrum-halves Murray and Lee Dickson being binned.
But that was as near as Northampton got. O'Gara extended the lead to 34-26 and then traded penalties with Lamb before Zebo intercepted on halfway nine minutes from time to kill the game. He completed his hat-trick three minutes from the end, with Scott Armstrong grabbing a late touchdown for a demoralised Northampton side.
Northampton: B Foden; J Elliott (S Armstrong 69), G Pisi, J Downey, V Artemyev; R Lamb (S Myler, 73), L Dickson (M Robert, 73); S Tonga'uiha (A Waller 67), D Hartley, B Mujati (P Doran Jones 65); S Manoa, M Sorenson (C Day 62); C Clark (B Nutley 62), P Dowson, R Wilson.
Munster: D Hurley; J Murphy, K Earls, L Mafi, S Zebo; R O'Gara (I Keatley 75), C Murray (T O'Leary 67); W du Preez (M Horan 55), D Varley (D Fogarty 75), BJ Botha (S Archer 75); Donncha O'Callaghan (M O'Driscoll 72), P O'Connell; D Ryan, P O'Mahony (Dave O'Callaghan 72), J Coughlan.
Referee: R Poite (France)
Sunday Indo Sport