A slithering try three minutes from time by Kyle Eastmond saved Saints when they looked set for their sixth Super League defeat of the season in the dourest of local derbies.
The league leaders appeared to have asked a little too much of their renowned crop of quality young players as they trailed going into the final minutes. But then the most exciting of them had one last thrust at the line, with the saturated turf allowing him to slide the last few metres for the vital points.
"That was the way to win the game in those conditions," said Eastmond's coach, Mick Potter. "He's very fast, he's very elusive and he showed there what he can do when he takes people on."
On a run of five victories, Wigan fans had no reason to go to Knowsley Road with their usual sense of foreboding. They did, however, soon fall behind. There was a good deal of luck involved in it, Paul Wellens coming into the line and putting in a speculative little kick. It took a convenient bounce off the outstretched foot of Thomas Leuluai and into the arms of Matt Gidley, who was left with little to do.
Wigan did well enough to get deep into Saints' territory a number of times after that, but lacked the composure to do a great deal when they got there. Their best chance came just before half-time, when Mark Flanagan broke away, only for Wellens to get back and cut him off. Wigan sustained the pressure, Leuluai's kick throwing Francis Meli into confusion and Sam Tomkins winning the race to touch down and Pat Richards' conversion putting them ahead at the break.
It took the return of the vastly experienced Keiron Cunningham and Tony Puletua from the bench to lift Saints in the second half, but they seemed to have lost their best chance when Lee Gilmour knocked on crossing the try-line.
But then came the 20-year-old Eastmond's decisive moment, adding the goal himself for good measure.
St Helens: Wellens; Gardner, Gidley, Gilmour, Meli; Pryce, Eastmond; Graham, Cunningham, Puletua, Wilkin, Flannery, Dixon. Substitutes used: Clough, Ashurst, Armstrong, Emmitt.
Wigan: Phelps; Roberts, Gleeson, Carmont, Richards; S Tomkins, Leuluai; Coley, Riddell, Prescott, Hansen, J Tomkins, Flanagan. Substitutes used: Paleaaesina, Fielden, Goulding, Mossop.
Referee: B Thaler (Wakefield).Reuse content