Castleford - needing a win to secure the fifth and final play-off spot - had already endured a miserable evening, stifled time and time again by their hosts’ impressive defence.
They were trailing 18-2 and had long run out of ideas when Sene-Lefao suffered his aberration - he apologised as he left the field, perhaps realising just what an awful mistake he had made - and now Daryl Powell’s side must hope Hull FC do not stun St Helens this evening.
If the Black and Whites, who have lost their last three games, can cause an upset against the leaders at KCOM Stadium in their final game, they will replace Castleford in fifth.
Tigers had shifted Hull down to sixth when stand-off Jake Trueman’s hat-trick helped beat them at Wheldon Road last week.
But just six days later, the young Great Britain hopeful found life far more difficult against the steely reigning champions who secured second spot with this seventh successive victory.
Trueman’s kicking game was badly off, twice rolling kicks dead to concede seven-tackle sets, and, despite a raft of good ball in both halves, he and the rest of his side failed to create anything of note.
Indeed, it looked like it would be the third successive visit to DW Stadium where they failed to score a try, losing 6-4 here in April and, of course, 14-0 in last year’s Super League semi-final.
However, Cheyse Blair saved them that ignominy when he crossed after the final hooter, capitalising on a Zak Hardaker error, but it was no consolation.
The West Yorkshire side had found impressive form of late but came up against a resolute side here who are mounting a charge that looks truly capable of causing Saints and the rest problems later down the line.
Back-to-back tries at the start of the second half did all the damage to Castleford who had trailed just 4-2 at the break.
Hardaker - whose infamous exit in Grand Final week scuppered their plans of a maiden title two years ago - was the first to go over after Oliver Gildart had set up position with a fine break up the middle.
Full-back Hardaker rolled in a grubber which Greg Minikin should have smothered but fumbled to gift his opponent the score.
Worse was to come in the restart set when Dan Sarginson evaded Trueman’s weak attempted tackle on halfway to surge clear again.
Although Minikin hauled him down, Joe Greenwood benefitted at the next play and then Castleford proceeded to waste more chances - Trueman throwing an intercept, Blair spilling under more pressure near the line.
Composed Wigan sat back, absorbed it all, nullified Tigers at every turn and then pounced again when they emerged at the other side, Gildart getting their next try.
After Sene-Lefao’s dismissal, Hardaker slotted a penalty and converted when Morgan Smithies rounded things off at the death.
Castleford should really have been ahead at the break but Jamie Ellis missed two simple penalties.
The first, after Greenwood’s dangerous tackle on Mike McMeeken, was perhaps defensible but the second, when a mistake-ridden Roman Navarrete caught Matt Cook high, was just 30m out in front of the posts.
It was the last kick of the half and Ellis could only leave one of the uprights rattling.
Otherwise, his side had been solid enough without looking particularly sharp.
Fortunately, Wigan were initially off the boil, too, rarely threatening Castleford’s line.
Their solitary breakthrough came from a typical piece of George Williams brilliance, the England stand-off shrugging off McMeeken’s tackle and then accelerating over from 20m in the 16th minute.
It was Wigan at their brutal best; moments earlier, Ellis had spilled to waste another promising attacking position at the other end and, after a cheap penalty carried them downfield, the hosts were over.
Still, Ellis - who opened the scoring with a tenth minute penalty - was not the only one miscuing with the boot; Hardaker skewed his conversion attempt wide much to the delight of the Castleford fans behind those posts.
Tigers needed to use the ball better but, after forcing a drop-out, Trueman ignored men outside to dab in a poor grubber that rolled dead.
Jordan Rankin was penalised for obstruction when he tried weaving over on the last tackle, Ellis had already rushed one play and there was no finesse to make their efforts count.
Things did not get better in the second period.
Wigan Warriors: Hardaker; French, Sarginson, Gildart, Burgess; Williams, Leuluai; Clubb, Powell, Partington, Isa, Greenwood, Smithies. Substitutes: Byrne, Navarette, Flower, O’Loughlin.
Wigan Warriors: Rankin; Clare, Mata’utia, Blair, Minikin; Trueman, Ellis; Watts, McShane, Millington, Sene-Lefao, McMeeken, Massey. Substitutes: Holmes, Cook, Clarkson, Smith.
Referee: James Child (Dewsbury)