|Wigan (4) 4|
|St Helens (16) 23|
|Tries: Percival, Knowles, Roby Goals: Percival 5 Drop-goal: Walsh|
Mark Percival scored 14 points for St Helens as they won a fiery derby against Wigan Warriors and secured a fifth straight Super League victory.
After Percival's early penalty, Lewis Tierney crossed for Wigan, but scores from Percival and Morgan Knowles put Saints 16-4 up at half-time.
Luke Walsh's drop-goal and James Roby's late try secured victory for the visitors in tricky, wet conditions.
Saints move up to fourth for the start of the Super 8s, as Wigan stay second.
With leaders Hull FC beating Salford, the Warriors missed the chance to stay level on points with the Black and Whites.
Wigan were on a nine-match winning run before their loss to Leeds last Friday, but will now go into their Challenge Cup semi-final against Hull FC next week following back-to-back defeats.
It was an impressive defensive effort throughout by Keiron Cunningham's St Helens side, highlighted when Joe Greenwood kept out Sam Tomkins' effort on the line in the second half.
New Zealand prop Frank-Paul Nuuausala was sent to the sin-bin on his home debut for Wigan for his strike on Louie McCarthy-Scarsbrook, who was also shown a yellow card.
Wigan forward John Batemen made his return after his eight-week ban and £10,000 fine for an alleged fracas with another player.
Wigan head coach Shaun Wane:
"I'm gutted, devastated. We didn't turn up and got what we deserved.
"The smartest team won. They were good on the floor and were allowed to be good.
"Our defence was very good for large parts of the game but our attack was off. Too many individual players had a poor game.
"We've got seven hard days of work ahead of us now. We need to make sure we turn up against Hull with the same commitment to defence but we've got to be better on attack."
St Helens head coach Keiron Cunningham:
"I'm just pleased for my players, they stood up to everything Wigan threw at us - they could probably still be playing now and not score.
"That's what self-belief brings to a side. We went through a tough spell but we're a real close-knit group and now we're heading in the right direction.
"Wigan are a great attacking side and were fully stacked tonight. They had lots of threats but I thought we stuck to the plan.
"We're not going to fall in love with ourselves, we give ourselves a good shot for the top four."
Wigan Warriors: S Tomkins; Tierney, Gildart, Sarginson, Manfredi; Williams, Smith; Sutton, Powell, Flower, Bateman, Isa, O'Loughlin.
Replacements: Crosby, Nuuausala, Mossop, Shorrocks.
St Helens: Lomax; Owens, Fleming, Percival, Swift; Turner, Walsh; Walmsley, Roby, Richards, Greenwood, McCarthy-Scarsbrook, Wilkin.
Replacements: Amor, Vea, Thompson, Knowles.
Referee: Phil Bentham.