They lost two men to the sin-bin and saw three others go off for treatment and not return, but were still led to a convincing victory by Keiron Cunningham, whose two tries packed a powerful, personal contribution.
"It was a victory marred by some unsavoury performances - the video will sort it out," said Saints' coach, Daniel Anderson, who lost Lee Gilmour with concussion and Sean Long and Darren Albert with facial injuries.
Saints found it ominously easy to open up Wigan down the flank after six minutes, the combination of Jamie Lyon and Albert doing the damage as so often this season. Joel Tomkins did remarkably well to chase back and deny Sean Long the try, but Cunningham was there to score from a deflected pass.
Tomkins was also involved in Wigan's equaliser, getting the final pass to David Vaealiki for a try which Sammy Tickle converted from a wide angle.
Tickle covered himself in less glory when he missed the tackle on Paul Wellens that allowed Saints a soft second try.
Wigan threatened to hit back when Dennis Moran intercepted Long's pass, Lyon going to the sin bin for delaying the play-the-ball.
Despite their numerical disadvantage, Saints immediately stretched their lead, Willie Talau shrugging off a series of tackles to send in Ade Gardner.
Their fourth try was simplicity itself, Cunningham simply muscling his way over from dummy half as Wigan began to look badly outgunned.
To their credit, they responded with a try of rare quality, Danny Orr kicking ahead for Vaealiki and the impressive Tomkins backing up to score.
Saints played the game safe when superb work from Cunningham and Jason Hooper released Jon Wilkin, who became the second Saint in the sin-bin when he charged in on Sculthorpe. Sheer strength took Maurie Fa'asavalau over to underline Saints' superiority.
* In last night's other Super League match, Salford dented London Broncos' play-off hopes with a convincing 26-18 victory at The Willows.
Wigan: Dallas; Carney, Brown, Vaealiki, Aspinwall; Orr, Moran; Guisset, Newton, Allen, Wild, Tomkins, Tickle. Substitutes used: Sculthorpe, Hansen, Beswick, Jewitt.
St Helens: Wellens; Albert, Lyon, Talau, Gardner; Hooper, Long; Fozzard, Cunningham, Anderson, Gilmour, Bennett, Roby. Substitutes used: Wilkin, Higham, Graham, Fa'asavalu.
Referee: I Smith.Reuse content