St Helens 6 Wigan Warriors 18
In an absorbing derby, they battled from 6-4 down at half-time to score three unanswered tries after the break from Thomas Leuluai, Bevan French and Jackson Hastings.
This was a full-bloodied contest full of needle, skill, passion, drama - and many ferocious exchanges - which would have been befitting the Grand Final in four weeks' time.
The margin of victory would have been greater had Zak Hardaker not missed three of his four conversion attempts, but this was a night to admire the positives in the Wigan performance - and they were plentiful.
Across the side, they showed an admirable amount of energy and character to claim the win, which sends them top of the table under the revamped win-percentage formula.
The only concern may be whether the RFL's match review panel charge Joe Greenwood after he was sinbinned in the late stages for a high tackle which sparked a melee.
Saints had won their previous two derbies this year, including beating a youthful Wigan line-up 42-0 a month ago.
But with Lam's side unchanged from the line-up which beat Salford 58-12 a week earlier - and Saints missing suspended prop Alex Walmsley - many were predicting a different, closer, full-bloodied derby... and they certainly got that.
The early exchanges were ferocious and quick, with committed defences stifling out any chances.
On a crisp night in a deserted Totally Wicked Stadium, the voices could be heard loud and clear - and Hardaker was persistently one of the most vocal.
Midway through the first half, the breakneck pace appeared to take its toll as errors began to creep in: Saints kicked out on the full, French's pass floated over the touchline... there was even a collision between James Graham and referee Chris Kendall.
Jonny Lomax appeared to be an early victim of the ferocity as he received treatment on a lower leg injury. But the ex-Orrell St James junior battled on and managed to provide the breakthrough, piercing Wigan's defence to send Lachlan Coote over for a try he converted just after the half-hour mark.
Wigan's response was swift and impressive. Greenwood came off the bench and immediately made an impact, breaking through and setting the platform for Leuluai to thread a ball through for Jake Bibby to ground in the corner.
Hardaker was wide with the conversion, giving the hosts a slender two point advantage at the break.
The tone continued into the second-half, and the longer it went on, the more it felt like a high-stakes, muscular blinking competition. A Saints blunder near their own line gave Wigan the golden field position from which Leuluai weaved through for his first try of the season to put his side ahead for the first time.
But Hardaker was again off-target, keeping Wigan's advantage at two points as the game edged into the final quarter.
This wasn't the type of game for fancy footwork, but French provided it anyway, blazing down the right touchline after some neat link-up from Leuluai and Willie Isa.
A three-tries-to-one lead should be comfortable, but with Hardaker again off target, they led just 12-6. Hastings, though, made the game safe moments later, combining with Greenwood to angle over for a try.
Hardaker's first conversion of the night wedged a 12 point gap between the sides with eight minutes to go and they finished strong, even when down to 12 men once Greenwood was sinbinned.
St Helens: Coote; Makinson, Naiqama, Welsby, Grace; Lomax, Fages; Graham, Roby, Lees, Taia, Bentley, Knowles. Subs: McCarthy-Scarsbrook, Peyroux, Amor, Paulo.
Wigan: French; Bibby, Hardaker, Gildart, J Burgess; Leuluai, Hastings; Bullock, Powell, Singleton, Isa, Farrell, Partington. Subs: Flower, Greenwood, Clubb, Smithies
Referee: Chris Kendall