LATICS produced their best performance of the season - but fell agonisingly short of the three points they thoroughly merited.
From the first whistle, the home side were on their game and created enough chances to have won half a dozen matches.
But a mixture of bad luck and poor finishing saw them having to settle for James McArthur’s scrappy goal eight minutes into the second half.
And there was a sickening sense of inevitability about the equaliser barely 10 minutes later, with former Latics star Paul Scharner popping up to nod in from close range.
Not even the second-half introduction of Momo Diame, Callum McManaman and Albert Crusat could tip the balance in Wigan’s favour.
Diame - just as was the case at Norwich last weekend - had a gilt-edged chance to make himself a hero with a tap-in from 10 yards in the dying seconds.
But again the finish was poor, and once more Latics were unable to force home a winning goal.
Roberto Martinez had made two changes to his starting XI, Shaun Maloney and Franco di Santo in for Jordi Gomez and the injured Hugo Rodallega.
Maloney’s inclusion had been a reward for his sparkling cameo at Carrow Road last weekend, and Latics picked up with the momentum that they finished that game.
In fact, they could easily have been four up inside four minutes.
With only 30 seconds on the clock, Di Santo got on the end of a long ball from the back but couldn’t keep his shot down.
The Argentine was then picked out by Jean Beausejour’s deep cross, but he was always on the stretch and volleyed wide of the target.
Moments later, James McCarthy rampaged forward before teeing up Di Santo, but this time the shot was tipped over by Ben Foster at the expense of a corner.
And from the resulting set-piece from Beausejour, skipper Gary Caldwell stole a march on his marker only to stab wide from eight yards.
Positively, the crowd stuck by Latics despite the near-misses, and the home side were nearly in again on six minutes.
Again the danger emanated from Beausejour down the left, and Di Santo appeared to be fouled by Gareth McAuley as the pair competed for the ball.
Referee Michael Oliver waved play on, however, and Emmerson Boyce lashed the rebound wide for a goal-kick.
Jerome Thomas pulled West Brom’s first opportunity well wide on the 10-minute mark, before Latics were back on the front foot.
Maynor Figueroa was encouraged forward to within 35 yards of the visitors’ goal and, although his shot was hopelessly off target, it was picked up by Victor Moses just inside the box.
The winger’s shot was superbly dealt with by Foster, who didn’t know the offside flag was up against Moses.
Foster was helpless on 16 minutes, though, as Latics carved out a clear chance that should have opened the scoring.
Beausejour once again sent over a marvellous cross from the left, which arrowed through the corridor of uncertainty towards the far post.
Coming in like an express train was Boyce, but he couldn’t keep his header down and, from inside the six-yard box, nodded against the bar and over.
The opening quarter had been as one-way traffic as there has been all season, and Martinez must have been wondering in the technical area how his side weren’t already out of sight.
There was a rare moment of concern at the other end as McAuley headed Chris Brunt’s free-kick five yards wide, which at least gave the visitors some respite.
West Brom then enjoyed a few minutes of decent possession, without really working Ali Al Habsi.
At the other end, Latics worked a promising break when McArthur found Moses in centre-field.
But the winger either didn’t see or chose to ignore Maloney, who’d taken up a great position on the left, opting instead to thread an impossible ball in the direction of Di Santo which was cut out.
Moses then saw a Beausejour cross taken off his head by McAuley, who headed over moments later at the other end from James Morrison’s far-post free-kick.
As half-time approached, Latics regained the ascendancy and came within a coat of paint of grabbing a deserved opener.
After Di Santo had got his head to a Maloney cross only to see the ball hit McAuley and deflect away to safety, McCarthy smacked a beauty from 25 yards that beat Foster but came back off the crossbar.
Moses looked a certain scorer from the rebound, only for the goalkeeper to regain his feet and claw the ball away.
It was head-in-hands time again two minutes before the break when Beausejour’s cross was nodded back across goal by Antolin Alcaraz, only for the ball to fall half a yard behind an unmarked Maloney.
Incredibly, there was more to come as Beausejour’s cross was completely misjudged by Foster and McAuley, but none of the three Wigan men inside the box read it and accepted what would have been a tap-in.
As the players trudged off at half-time, it was heartening to hear the home crowd that had been so vocal in their criticism during the last home game against Swansea this time so supportive of their team’s efforts.
And it was more of the same at the start of the second-half, as Maloney showed lovely skill to bamboozle his marker before testing Foster with an early shot.
A rare Baggies counter-attack threatened danger, but a lung-busting 60-yard chase by McCarthy not only snuffed out the danger but won a throw-in for his side.
Then, eight minutes after the restart, came the goal that Latics had worked so hard to fashion.
Moses it was who weaved his way to the byline down the right-hand side, and his cross wasn’t cleared by McAuley - which allowed McArthur to toe home from a yard.
It was the scrapiest goal imagineable, but there won’t have been a more well-earned goal scored all season.
In typical Latics style, West Brom almost levelled within a minute, Jerome Thomas racing down the middle and was only pegged back by a timely last-ditch challenge by Boyce.
As the hour mark came and went, it was impossible to get away from the feeling that the next half-an-hour would go a long way towards shaping Wigan’s entire campaign.
And the home side signalled their intent by continuing their attacking as they went in search of the all-important second goal.
Scharner and Brunt had their names taken in the space of two minutes for hauling down Figueroa and Di Santo respectively, before Alcaraz nearly got on the end of a nice free-kick from Maloney.
You always got the impression that Latics would need a second goal to clinch the victory, and that point was hammered home with 25 minutes remaining as the Baggies equalised.
Brunt’s delivery from a right-wing corner was superb, and Scharner - of all people - escaped the clutches of Alcaraz and nodded home from inside the six-yard box.
There was another key moment as the game entered the final quarter, when Youssouf Mulumbu reacted ridiculously over-the-top to a simple foul by McArthur, which sparked a melee involving most of the players.
After consulting with his assistant on the near side, referee Oliver chose to only book Mulumbu, as well as Boyce and Thomas for their part in the aftermath.
That was Mulumbu’s last action, before being withdrawn for Keith Andrews.
Martinez, too, made his move, taking off McCarthy and Maloney and sending on Callum McManaman and Diame for the last 10 minutes.
Andrews nearly made an immediate impression, finding the ball at his feet following a razor-sharp Albion counter only to find the side-netting as opposed to the back of the net.
McManaman then had a similarly golden opportunity to make a name for himself within seconds, Boyce finding him unmarked at the far post with the defence stretched.
But instead of pulling the trigger, the youngster seemed to get caught in two minds and, in the end, lost the ball under his feet - and compounded his error by diving in on the Albion defender and becoming the latest name in the book.
Graham Dorrans replaced Thomas for Albion, and his first touch was to guide the ball away from Boyce as the Wigan full-back tried to get on the end of a Beausejour cross.
Another delivery from the Chilean was headed well wide by Moses, before Martinez played his final hand, Albert Crusat for Figueroa.
Crusat’s first touch was to release Beausejour on the overlap, and the pull-back found Diame in acres of space on the penalty spot.
But just as he did last week, the midfielder snatched at the chance and his shot was woefully off the mark.
Crusat was finding space with ease, and his injury-time cross was deflected goalwards, only for Foster to throw out a right arm and touch it round the post.
It had been one of thosse days.
Latics: Al Habsi 7; Alcaraz 7, Caldwell 8, Figueroa 7; Boyce 7, McCarthy 8, McArthur 8, Beausejour 8; Moses 7, Maloney 7; Di Santo 7.
Subs: Kirkland, Stam, Watson, Diame (for McCarthy, 80), Crusat (for Figueroa, 87), McManaman (for Maloney, 80), Gomez.
West Brom: Foster; Jones, McAuley, Ridgewell, Shorey; Thomas, Scharner, Mulumbu, Morrison, Brunt; Long.
Subs: Daniels, Andrews (for Mulumbu, 80), Dorrans (for Thomas, 86), Dawson, Tamas, Cox, Fortune.