Article continues below
Widnes demonstrated their table-topping feat is no fluke as they condemned Wigan to their first defeat of the season and a first home loss in Super League for 21 months.
The Vikings over-turned an 8-0 half-time deficit to secure a tense 18-12 victory and open up a two-point lead after making their best ever s tart to a Super League campaign.
With both teams scoring three tries, the outcome came down to goalkicking, with Matty Smith missing all his three attempts for the Warriors and Rhys Hanbury kicking three from four for the visitors.
But the Vikings were good value for their sixth victory of the season, which was especially sweet for skipper Kevin Brown, who was on the losing Wigan side when Widnes last triumphed at the DW Stadium in 2003.
Widnes, already without centre Chris Bridge through injury, lost hooker Lloyd White through illness before kick-off but Aaron Heremaia was a superb replacement in another impressive team display by Denis Betts' men.
It was the best defence in Super League up against the best attack and the Vikings' flair eventually told.
Scrum-half Joe Mellor, one of five former Wigan players in the Widnes starting line-up, and Brown were both tackled agonisingly short of the line early in the game and centre Chris Dean was held up on his back as the Warriors demonstrated their defensive resolve.
The opening try came during a promising attack from the visitors, with Wigan's England forward Liam Farrell intercepting Mellor's offload to sprint 80 metres unchallenged.
The Vikings defended just as stoutly as the home side but they were undone six minutes before half-time when Dan Sarginson, who added a new dimension to Wigan's attack from full-back, fired out a cut-out pass to get left winger Josh Charnley over for the second try of the game.
Smith was side with both difficult conversion attempts and was also off target with a long-range drop goal attempt on the stroke of half-time when the Warriors led 8-0.
It looked a tenuous advantage even before Widnes dominated the start of the second half to peg back the lead.
Mellor had a try disallowed by video referee Phil Bentham for offside but the Vikings were able to maintain the pressure courtesy of a knock-on by O'Loughlin and second rower Matt Whitley took Mellor's short pass to crash over for a try.
Hanbury's goal cut the deficit to two points and Widnes would have been in front had winger Corey Thompson, Super League's leading tryscorer, been able to get a hand to Brown's kick to the corner.
Wigan survived and scored a third try on 53 minutes when Thompson failed to deal with O'Loughlin's high kick and Charnley picked up the loose ball to dive over for his second try.
For the third time, Smith was unable to add the goal and the Vikings struck back with two tries in three minutes around the hour to go in front for the first time.
Left centre Charly Runciman worked his winger Stefan Marsh over at the corner for his ninth try of the season and then supported a break by full-back Hanbury to touch down himself.
Hanbury kicked a second conversion to make it 16-12 and extended the lead with a 72nd-minute penalty, which proved to be the last score as Widnes held off a determined last-ditch bid by their hosts to snatch a draw.