Warrington captain Lee Briers kicked a 78th-minute penalty to give the Wolves a last ditch derby win over Wigan.
The hosts were desperate for a win having claimed just one in seven, and Briers held his nerve at the death to give his side a crucial win as they aim to secure their place in the play-offs.
Early tries by Martin Gleeson and Toa Kohe-Love put the hosts in front but Wigan - themselves on a five-game winning streak - fought back and drew level with second-half tries by Sean O'Loughlin and replacement Danny Tickle.
Warrington prop Paul Wood and Wigan full-back Chris Ashton then exchanged tries before Briers won the kicking battle with Wigan's Michael Dobson, who moments earlier screwed a drop-goal attempt wide.
Huddersfield Giants 34 Castleford Tigers 10
Huddersfield will go into their Challenge Cup semi-final against Leeds buoyed by successive wins after a battling 34-10 victory over Castleford on Sunday afternoon.
Having come from behind against Wakefield to end a run of four straight engage Super League defeats last week, the Giants again needed to dig deep to see off the battling Tigers.
Brad Drew, Kevin Brown, Andy Raleigh, Jim Gannon, Chris Nero and Martin Aspinwall all crossed for the Giants on an eventful afternoon at the Galpharm Stadium, which saw Castleford's Danny Brough sent off.
The game proved a baptism of fire for rookie referee Jamie Leahy, who was controlling his first Super League match.
Brough was dismissed for reacting angrily to be being sin-binned late in the game while there were also a number of calls which infuriated the home side.
Leeds Rhinos 14 St Helens 18
St Helens overcame the dismissal of Man of Steel Jamie Lyon to lay one hand on the engage Super League leaders' trophy after completing the double over their nearest rivals Leeds.
Leeds had a late try by Ashley Gibson disallowed as Saints shaded their Roses showdown to open up a six-point lead, with six matches left of the regular season.
But their first victory at Headingley for four years was marred by the sending-off of Lyon 12 minutes from the end for a late and high tackle on Leeds' Rob Burrow.
Thunder and lightning outside the ground was matched by the stormy atmosphere on the pitch for a pulsating match watched by a 17,700 crowd, the Rhinos' fifth sell-out of the year.
Harlequins RL 18 Hull FC 16
A first-half hat-trick from Australian full-back Mark McLinden proved just enough for Harlequins as they ended Hull's 13-match engage Super League winning streak with an 18-16 home win.
The London outfit made the dream start when McLinden intercepted a Sid Domic kick before a lightning break saw the Aussie star complete an 85-metre run to touch down under the posts.
They continued to dominate and went in 18-2 ahead at the break.
After the break though the game turned full circle.
McLinden made a brave last-ditch challenge to deny a Hull attack a yard from the line but he paid the price for his commitment and was helped off the field with severe concussion.
Hull stepped up a gear after McLinden's departure and in the 50th minute Domic registered their first try - a deep Chris Chester kick was not dealt with by Bradley-Qalilawa and Domic pounced.
With their tails up Hull then scored again as Motu Tony - who signed a three-year extension to his Hull contract on Thursday - took full advantage of another Quins lapse to score in the right corner.
Purdham then wasted a golden opportunity to seal victory for Harlequins as following a darting run inside the Hull half he kicked into the corner instead of flicking the ball inside to the screaming Bradley-Qalilawa.
In the final minute Hull's Nathan Blacklock flew down the right wing to score but despite Dixon kicking the conversion there simply was not time for the visitors to set up another scoring position as Harlequins scrambled the victory to move five points clear of the drop-zone.
Catalans Dragons 26 Salford City Reds 6
Catalans Dragons climbed off the foot of the engage Super League table as they powered to an emphatic home victory against Salford.
The Dragons' maiden season in the league has seen them fall short of the standards required to contend the top or even mid-table places.
But after a five-try rout of Salford, they are now strongly placed to avoid the wooden spoon.
David Waite's team took an early grip on proceedings at the Stade Aime Giral.
Australian Chris Beattie crossed for the game's opening try in the 12th minute after good work by Stacey Jones, and Jones duly kicked the extras, to give the Dragons the start they wanted.
Sean Rudder, another Australian, ran in the second 10 minutes later as Salford - who came into the match in a healthy sixth place - found the going tough.
Again Jones kicked the goal as the home side gave themselves a 12-point cushion early in the match.
When New Zealand superstar Jones crossed for the third Dragons try, and booted his third goal, there seemed little doubt where the points were going.
Justin Murphy became the third Australian to touch down when he added the fourth Catalans try in the 61st minute, and his second score arrived 12 minutes later to put the seal on a handsome victory.
Between his tries, prop Andy Coley scored a consolation try for Salford - and David Hodgson added the extras. But it was largely a grim night for the English visitors to Perpignan as the Dragons produced some of their best rugby of the year.
Wakefield Trinity Wildcats 20 Bradford Bulls 42
Wakefield slipped deeper into engage Super League relegation trouble after going down to their seventh defeat in eight matches, 42-20 against Bradford.
The Wildcats, without a coach following the departure this week of Tony Smith, were also lacking ideas in a dreadful first half in which they found themselves trailing 24-0 to the reigning champions.
Quick-fire tries from former Bradford centre Ryan Atkins either side of the interval and a marked improvement in the second half enabled the home side to restore some pride but it was never going to be enough to make up for a shoddy first 40 minutes.
The Wildcats, two points adrift of Wigan, still have six matches left to save themselves from the drop but, on this performance, whoever takes over as coach faces a thankless task.
Jamie Langley and Karl Pryce both grabbed two tries for the Bulls with Paul Deacon kicking seven goals.