Wigan have not been beaten at their stronghold by a British team since Wakefield Trinity three years ago; Saints had not managed it for the best part of a decade.
At half-time, with a Wigan lead of eight points looking a useful one in the context of such a hard-fought match, it looked as though they might have to wait a while longer.
But that was when Pickavance, a first-half replacement for the injured Derek McVey, took over. Four minutes into the half, he capitalised on sustained St Helens pressure with an angled run to claim their first try, with Lee Briers, Eric Hughes' parting gift to Saints as his last signing before being sacked as their coach, landing the first of his three goals.
Within another five minutes, Pickavance had made a storming run from halfway and threw out a long pass to Anthony Sullivan, who beat Doc Murray on the outside to touchdown for Saints' second.
A penalty from the Wigan captain, Andy Farrell, brought them back within two points, but then another charging run from Pickavance set up the position from which Karle Hammond and Alan Hunte made the most of the limited space available to send in Danny Arnold at the corner.
It added up to a devastating contribution from a player rarely mentioned among Saints' potential match-winners.
Another of Saints' in-built advantages at the moment is that there is no more potent combination in the game than that between Hammond and Hunte.
Hammond had the dislocating experience of being switched from loose forward to stand-off five minutes before the game when Tommy Martyn aggravated a thigh injury in the warm-up, but he again showed what a high-class player he has become. His short pass to release Hunte for the final Saints try was a case in point.
Wigan finished well beaten, their 55-match run at Central Park now just a receding memory, but they had been the better team by some distance in the first half.
A contest of few clear-cut scoring opportunities but constant thrust and counter thrust started to tilt the home team's way when Farrell put over an early penalty.
After 34 minutes, it was a Farrell kick that saw Steve Prescott caught in his in-goal area and, as Wigan turned the screw, Gary Connolly found a way over from acting half.
Farrell's conversion completed a handy lead, but by that time Wigan had already suffered a blow that was to affect them badly as the game went on. Henry Paul, who played for the Wakefield side that was the last to win a league game at Central Park, was helped off with his back in a spasm and later went to hospital for a precautionary X-ray.
With Tony Smith making his debut at scrum-half, Wigan now lacked a half- back used to working with their first team line-up and that played a part in the way they faded in the second half.
Smith showed enough of the incisiveness for which Wigan have bought him during the first half to suggest that he will be a sound investment and he could have scored a try shortly before half-time that would have made Wigan's lead much harder to overturn.
Prescott's tackle kept him out, however, and Saints remained sufficiently in touch to set the stage for their revival.
"It's one of our best victories, no doubt about it," Shaun McRae, the St Helens coach, said. "But it's only worth two points."
Hughes, denied the pleasure of revenge over the club that dispensed with his services, came away with his strongest impressions about the job that lies ahead at Wigan confirmed. He wants his squad strengthening in both senses; both in terms of numbers and in building up the power of players who were increasingly out-muscled by Saints.
Wigan Warriors: Murray; A Johnson, Connolly, Radlinski, Robinson; Paul, Smith; O'Connor, Cassidy, Cowie, Haughton, Tallec, Farrell. Substitutes used: Murdock, Long, Holgate.
St Helens: Prescott; Arnold, Hunte, Newlove, Sullivan; Hammond, Briers; Perelini, Cunningham, O'Neill, McVey, Morley, Joynt. Substitutes used: Pickavance, Matautia, Northey.
Referee: D Campbell (Widnes).
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