Wigan’s lethal left edge ensured Shaun Wane maintained his perfect Good Friday record against 12-man St Helens.
Liam Marshall and his centre, Joe Burgess, scored two tries each as the Warriors marched to their eighth-straight victory in the traditional Easter weekend derby.
Liam Farrell also chipped in with a try against Saints, who saw prop Kyle Amor red-carded in the 13th minute for a high shot on Marshall.
The home side led 8-2 at half-time, Burgess scoring the only try until that point. Saints threatened, briefly, in the second-half when a try by exciting debutant Regan Grace cut the scoreline to 15-12.
But from that point, the Warriors finished strongly with three tries in a whirlwind seven-minute spell to pull clear of their fierce rivals.
Both sides headed into the game with some poor recent results, testing the mantra that form goes out the window for this derby showdown.
As expected, Wigan welcomed back four key players from injury - Sean O’Loughlin, Joe Burgess, Anthony Gelling and Micky McIlorum.
Hooker McIlorum, back from a 14-month absence with a broken ankle, was introduced before half-time to loud applause from the home fans among the 23,390 - the seventh biggest-ever Super League crowd.
Saints lost full-back Jonny Lomax to a deadleg in the build-up and, in the reshuffle, Welsh youngster Grace came onto the wing - an unusual case of a player making his Super League debut after he had played for his country.
The interest with Saints, of course, centred on how they would react to the sacking of Keiron Cunningham earlier in the week. They met Wigan’s challenge head on in the opening exchanges. But the major flashpoint came in the 13th minute, when Amor was red-carded for a high swinging arm on Marshall.
Ben Thaler’s decision polarised opinion, with replays suggesting Amor’s arm made initial contact with the ball. It certainly stretched Saints’ hopes of ending Wigan’s grapple-hold of recent Good Friday derbies.
The game opened up, with both sides having half-chances - Ryan Morgan was brought back for a knock-on and Liam Farrell was denied a certain-try for a forward pass in the build-up.
After Theo Fages slipped beyond Ben Flower, and was hauled down by fellow Frenchman Morgan Escare, it gave Saints the position to nudge 2-0 ahead through a Mark Percival penalty.
But Williams, who this week pledged his future to hometown club, skidded a kick into the ingoal and Burgess managed to ground. It was his seventh try in five games back with Wigan, and also stretched his own personal record of scoring in all his three Good Friday derbies.
Wigan began to dominate, with possession and in terms of position, pinning Saints into their own half, forcing repeat sets and building pressure.
Saints scrambled well defensively, but choked of the ball, there was a sense of inevitability to Wigan extending their lead - though it came from the boot of Escare from a 37th minute penalty, adding to his earlier conversion to make it 8-2 at the break.
If the mood at half-time was that St Helens would fade in the second-half, they showed no signs of that from the restart as debutant Grace shows great pace and footwork to zig-zag down field, setting up the position for Morgan Knowles’ try. Percival’s conversion locked the score 8-8.
Wigan’s responded with confidence and no shortage of class, working their way down field and Marshall finishing off a right-to-left attack - Williams with a wonderful looping ball.
Saints, though, just wouldn’t fade away and when the otherwise excellent Farrell lost the ball, it gave the visitors the chance to respond, which they did with grace with a try from, erm, Grace. Percival’s conversion attempt was wide, keeping a three-point margin between the sides.
But Grace’s error from the kick-off gave Wigan an early, and easy, chance to reply before the hour-mark - and they quickly killed the game off with an imperious, three-try purple patch.
First, Farrell dummied a pass and crossed to make it 19-12 and, moments later, the England forward sent Marshall clear from near halfway, the winger turning on the afterburners and having the poise to acrobatically touch down in the corner under Tommy Makinson’s desperate lunge.
Their next try was nearly as stylish, Burgess angling in to regather Williams’ measured kick and slide over. Escare hit one of the three conversions to take the score to 29-12 - and allow fans to enjoy the last few minutes.
Makinson pulled a try back, which he converted, but Wigan remained on course for their first win in five matches.
Wane now takes his side to Wakefield on Easter Monday.
Wigan: Escare; Davies, Gelling, Burgess, Marshall; Williams, Leuluai; Nuuausala, Powell, Flower, Tomkins, Farrell, O’Loughlin. Subs: Tautai, Sutton, Isa, McIlorum.
St Helens: Makinson; Grace, Percival, Morgan, Swift; Fages, Smith; Amor, Lee, Douglas, Taia, Wilkinon, McCarthy-Scarsbrook. Subs: Walmsley, Thompson, Richards, Knowles.
Referee: Ben Thaler
Starman: Liam Farrell