Ulster, last season's Heineken Cup runners-up, entered the Franklin's Gardens bearpit unbeaten in all competitions this season, and unbeaten they remain.
Driven along by an indefatigable back-row unit of Iain Henderson, Chris Henry and the former Northampton No 8 Roger Wilson, they made a rare old mess of their hosts in the loose and gave the brilliant Springbok half-back Ruan Pienaar all the time he needed to run the show with customary precision.
Unless the Midlanders do something remarkable back at Belfast's Ravenhill next weekend, their European campaign will be over.
Northampton were acutely aware of the importance of this game following the disappointing defeat at Castres in the previous round and they were full of hostile intent in the early stages.
Paddy Jackson, the fresh-faced little cherub in the Ulster No 10 shirt, was far from reliable from the kicking tee, but his hanging punt to the left corner following a fierce forward churn from a line-out was sufficiently accurate to give Andrew Trimble the faintest whiff of a try. True to form – he looked every inch an international wing last night – Trimble maximised the limited space available to him and beat Ben Foden to the touchdown.
Lamb and Jackson then swapped penalties – their successes were very much the exception rather than the rule – before Ulster dealt a serious body blow by scoring a second try.
Jared Payne set things rolling with a pinpoint kick to the left flag, thereby putting serious pressure on Dylan Hartley's line-out throw. Hartley threw long…and threw wrong. The men from Belfast snaffled possession, Henderson twice kept the siege alive with powerful work in contact and when the midfielders finally put some width on the ball, there was no stopping Tommy Bowe on the overlap.
Within five minutes of the restart, the centre Darren Cave burst away from Calum Clark in open field to launch another Ulster attack and Trimble sprinted off his wing to find Payne with a beautiful running pass that left the full-back to sell Foden down the longest of rivers with an old-fashioned dummy and complete the killer score.
Things grew a little fractious in the final quarter – the two international hookers, Hartley and Rory Best, had a serious falling-out, with fists and elbows prominent – and as the temperature increased, Henderson was pointed towards the cooler. It mattered not one jot. At the very last knockings, Payne set sail once again in broken field and presented the lock Dan Tuohy with the bonus-point try.
Scorers: Northampton: Penalties Lamb 2. Ulster: Tries Trimble, Bowe, Payne, Tuohy. Conversion Jackson. Penalty Jackson.
Northampton BB Foden; K Pisi, G Pisi, D Waldouck (T May, 67), J Elliott; R Lamb (S Myler, 60), M Roberts (L Dickson, 51); S Tonga'uiha (A Waller 63), D Hartley (capt, M Haywood, 71), B Mujati (P Doran-Jones, 60), S Manoa, C Lawes, C Clark (P Dowson, 57), T Wood, G-J Van Velze.
Ulster J Payne; T Bowe, D Cave, P Wallace (L Marshall, 69), A Trimble (C Gilroy, 69); P Jackson, R Pienaar; T Court (C Black, 69), R Best, J Afoa, J Muller (capt, N Williams, 50), D Tuohy, I Henderson, C Henry, R Wilson.
Referee J Garces (France)