Wigan lay down a marker of their own title credentials with an emphatic victory against their nearest and fiercest rivals.
They were always in front in this absorbing derby but - for an hour - it was a tense encounter until they pulled clear with tries by the returning Oliver Gildart and Sean O’Loughlin.
The passion, quality, skill and atmosphere of this game helped ignite the Super-8s. And Wigan’s win delayed the presentation of the league leaders’ shield to St Helens, while also strengthening their grip on second spot, a position rewarded with a home semi-final.
Shaun Wane had said he wanted another game to add to his own highlights reels of derby away-day wins - he wasn’t disappointed.
Their performance had desperation and desire and - on top of that - their attack was spiced with ad hoc plays and adventure. Wigan led 14-4 at half-time and, while Saints closed the gap to eight points, the visitors finished the stronger.
Former Saint Joe Greenwood was a potent threat on the left flank, George Williams and Morgan Escare added the sparkle, John Bateman the mongrel, while Ben Flower and Tony Clubb were authoritative figures in the middle.
But they all played their part as they claimed their first derby win of the season, following defeats in July and on Good Friday.
The drama began before kick-off.
Sam Tomkins was named on the teamsheet and emerged for the warm-up, his thigh heavily strapped, but left the pitch minutes later and withdrew.
It meant travelling reserve Ollie Partington stepped into the squad for his third senior game, and Escare was promoted from the bench to the full-back role.
The livewire Frenchman quickly made his mark, taking Greenwood’s sweet pass and blazing through to send Dan Sarginson over for a third-minute opener.
Saints, though, have exhibited their quality throughout this year and roared down field for Danny Richardson to put Louis McCarthy-Scarsbrook charging through a gap, only for the video referee to rule out a try for interference in the build-up.
The extra official was called on moments later, ruling out a Sam Powell try for a knock-on by John Bateman in the build-up. It was breathless, pulsating, end-to-end excitement - and there was no shortage of grit, either, with Willie Isa playing on after running repairs on a dislocated finger.
Wigan’s defence was admirable. Escare tracked down a breakaway Ben Barba and - with James Roby a menace from dummy-half - it needed a strong, well-marshalled line to deny the hosts.
They countered spectacularly, Sarginson again scoring and Greenwood again instrumental in its creation with a surging break. Escare, lively with the ball, was not as impressive kicking it as he again sent his conversion attempt wide.
Wigan held an 8-0 lead heading into the final five minutes of the opening half but there was still time for each to score a try, Bateman’s determined run converted by George Williams before Tommy Makinson did exceptionally well to beat Gildart to a crossfield kick.
But from the restart, the Warriors wasted little time in restoring their 14 point advantage. Williams and Greenwood again caused the trouble down the left and, when the ball was swung to the opposite flank, Tom Davies was able to ground the ball through a congested defence.
Davies pierced Saints’ defence on an angled run and, after a manic spell from both teams - forced passes, intercepts, spills - the hosts replied, Makinson profiting from Louis McCarthy-Scarsbrook’s offload.
Richardson nailed the sideline conversion to cut Wigan’s advantage to 18-10 - and they sniffed a comeback.
O’Loughlin returned to steady the shop in the final quarter as the game settled into a heavyweight blinking competition of completed sets and long kicks. A fumble by Escare had the Wigan fans worried, but they survived - and countered with a breathtaking try which opened up a three-score lead.
Greenwood again wreaked havoc down the left, unleashing Gildart and the player who scored two tries in this corresponding fixture a year ago turned on the afterburners and turned Barba inside out to score. Williams’ goal made it 24-10 - and they still weren’t done.
O’Loughlin went over from short-range, Williams tagged on the extras, and with seconds to go they frantically tried to swell their winning margin, only for Saints to hold out.
Wigan, who host Wakefield on Thursday, moved five points clear of Castleford ahead of their game against Challenge Cup winners Catalans.
St Helens: Barba; Makinson, Morgan, Percival, Grace; Lomax, Richardson; Douglas, Roby, Thompson, McCarthy-Scarsbrook, Taia, Knowles. Subs: Amor, Wilkin, Lees, Ashworth.
Wigan: Escare; Davies, Isa, Sarginson, Gildart; Williams, Leuluai; Navarrete, Powell, Flower, Greenwood, Bateman, O’Loughlin. Subs: Clubb, Sutton, Partington, Hamlin.
Referee: Chris Kendall
Starman: Joe Greenwood