Wigan Warriors stunned their arch-rivals St Helens 18-6 at the Totally Wicked stadium in the race for top.
The result sees Wigan leapfrog the Saints to the top of the Betfred Super League with only three rounds remaining.
Story of the match
In what proved to be a tight opening half an hour between the two old rivals, were tempers flared now and again, it was St Helens who drew first blood.
Jonny Lomax shrugged off an earlier injury to break through the Wigan defence before his inside pass sent Lachlan Coote easing over.
Coote converted but the Warriors soon struck back as a line break from former St Helens player Joe Greenwood gave Wigan some favourable field position before a grubber kick from Zak Hardaker was collected by Jake Bibby, who scored in the corner.
Hardaker was wide with his conversion attempt, leaving the Saints with their slender lead at the break.
The Saints came close to scoring again as Regan Grace chased down a grubber kick, only for it to bounce in-goal for a 20 metre restart.
Wigan then weathered the storm as a knock-on by Grace gifted the Warriors another set before Thomas Leuluai dropped his shoulder and scored from ten metres.
After then surviving another St Helens attack, Wigan soon scored their third try.
A decisive offload from Willie Isa put Bevan French into space, who then skipped round Coote to score and take his side into double figures.
Then with only ten minutes remaining, Wigan did enough to seal the win as Man of Steel Jackson Hastings collected a return offload from Greenwood to score.
Then during the closing stages, both sides became involved in a few bust-ups.
This eventually culminated in a high tackle by Greenwood, who was sin-binned for the incursion.
However, Wigan survived with the 12-man and held on to a memorable win over their nearest and dearest.