Saints held their nerve and just about kept their line intact to grab an important derby win at Wigan.
They did so despite losing linchpin Luke Walsh early in the first half, but in his place once again Jon Wilkin stepped into the breach.
In pleasing contrast to the defeat by Shaun Wane's mob on Good Friday, Saints came out this time firing on all cylinders up front.
Sia Soliola led by example in the middle and at long last Mose Masoe fulfilled his role as an enforcer in arguably his best game in the red vee.
And at the the back Paul Wellens was once again exemplary, with the steadying Lance Hohaia once again showing his value to the team and Tommy Makinson providing the finishing touches.
Saint were pretty dominant in the fierce opening exchanges, but a couple of early Wigan penalties took the initial sting out of that opening onslaught.
In fact Wigan penalties were a feature of the evening - and they also played a part at the back end of the game.
The reigning champions were able to counter effectively and nine minutes in wing Joe Burgess won the race to touch down Sam Powell's kick wide.
With Masoe entering the fray, Saints continued to edge the physical battle for once, with the Samoan World Cup prop bumping off Dom Crosby to get them on the front foot.
And for the second week running Mark Flanagan produced a great try scoring pass to send Makinson scampering in at the corner at the quarter mark.
The remainder of the half was scoreless, but not without incident and it was clearly bubbling up into a derby to remember.
Saints were first out of the blocks at the start of the second half and after a Wilkin kick bounced Wellens was presented with a run to the line from Luke Thompson and he duly obliged.
Saints tried to extend that lead but were foiled by a couple go handling errors, and then Wigan were awarded a massive pressure relieving penalty.
The Warriors cranked up the pressure at the other end and then at the end of the set the ball was flashed wide for Josh Charnley to dash in at the corner.
Matty Smith was unable improve so the scores were level at 8-8, but Saints were determined that this was not going to be a momentum turner.
And a marvellous chase from Soliola, after a deep kick from Wilkin, forced Charnley back behind his line.
Saints cranked up the pressure from there they were awarded a penalty for a high tackle, which Mark Percival duly converted to nudge them into a lead that they would not lose.
After Wigan were penalised for lifting Masoe's leg, Saints countered with the try of the match.
A Masoe offload set the ball rolling, with the ball spread to the flanks where Makinson again slipped the tackles en route to the line.
Percival kicked a magificemt kick from the touchline and the Saints fans roared with approval.
But Wigan were able to monopolise play in the final 10 minutes and looked like they were over, but Burgess was penalised for a double movement.
But the pressure on the Saints line was not relieved for long, and after another drop out, Wigan made it count with the ball floated wide for Charnley to cross two minutes from time.
Although Smith missed the conversion - a brace of penalties send the nail biters into fever pitch but Saints held on for a win that was vital, not simply to keep them on top of the pile, but also for bragging rights.
Wigan: Bowen; Charnley, Sarginson, Gelling, Burgess; Powell, Smith; Flower, Williams, Dudson, Hughes, Bateman, O'Loughlin. Subs: Taylor, Crosby, James, Doran.
Saints: Wellens; Makinson, Turner, Percival, Swift; Hohaia, Walsh; Richards, Roby, Walmsley, Flanagan, Wilkin, Soliola. Subs: Masoe, Manu, McCarthy-Scarsbrook, Thompson.
Ref: P. Bentham.