First defeat for Saints caretaker coaches Rush and Cunningham
Wigan won the first Super League derby clash at Langtree Park with a 28-10 victory over their fiercest rivals.St Helens were threatening a second-half comeback after getting to within two points of Wigan, but Sam Tomkins' try from a superb Gareth Hock offload gave the visitors breathing room.
They completed the win with late scores from Hock and Jeff Lima to end Saints caretaker coaches Mike Rush and Keiron Cunningham's winning start in the role.
Saints never really recovered from the shock of losing scrum-half Jonny Lomax with a badly broken thumb after just 16 minutes.
But Wigan props Hock and Lima helped make light of the absence of five first-choice forwards through injury and suspension and it was fitting that they scored the late tries that secured victory.
Early handling errors by Tom Makinson, deputising for the suspended Paul Wellens, and Wigan pivot Brett Finch demonstrated big match nerves in front of the 18,000 sell-out crowd.
There was also an uncharacteristic blunder from Tomkins which gifted Saints the game's first try, although he went on to more than make amends.
The England star lost the ball in Josh Jones' tackle and Lance Hohaia reacted quickly to get Francis Meli over at the corner despite Josh Charnley's last-ditch tackle.
Undeterred, Wigan roared back and dominated the rest of the first half to open up a 12-4 lead.
Centre Darrell Goulding took Thomas Leuluai's pass to cross for an equalising score after Saints' passing broke down 30 metres from their own line and, after Pat Richards was denied a try for a foot in touch, George Carmont demonstrated his strength to reach out of a three-man tackle to touch down.
The visitors would have been further ahead but for some tremendous defence on his own line by Saints second rower Sia Soliola, who managed to prevent substitute three-quarter Jack Hughes grounding the ball.
St Helens were a rejuvenated side in the opening exganges of the second half and it took some exceptional defence to keep them out.
Three successive penalties close to the Wigan line eventually proved decisive, with Soliola making the pressure tell by crashing over for his side's second try.
Makinson added the goal to make it 12-10 and Saints should have regained the lead only for Roby to lose the ball going for the line and that mistake quickly proved costly.
Wigan powered their way to the other end of the field and Hock's brilliant back-of-the-hand offload sent Tomkins jinking in for an eighth try of the season.
Wigan wanted a penalty try when centre Michael Shenton pulled back Goulding as he chased his own kick, but video referee James Child was not convinced a try was certain.
However, Shenton was sin-binned for the professional foul and Wigan quickly made the extra man count with Finch sending Hock through a gap for the clinching try.
With the game over as a contest, Lima added some extra delight for the visiting fans by crashing through an exhausted defence for Wigan's fifth try.