A STUNNER from birthday boy Victor Moses and a third goal in four matches from Jordi Gomez saw Latics pick up their second away win on the bounce - and temporarily move out of the bottom three.
Despite trailing to a brilliant free-kick from Baggies right-back Steven Reid, Latics showed their bouncebackability to equalise within three minutes through Moses’ first goal in 13 months.
And they picked up all three points when Moses was felled in the area by Reid on the hour mark and Gomez sent Ben Foster the wrong way from 12 yards.
It was real backs-to-the-wall stuff in the final third as the home side threw everything at the visitors.
But the Latics rearguard remained resolute and survived the late loss of Antolin Alcaraz with a suspected cracked rib to emerge victorious.
Twelve months ago Latics had led 2-1 going into the final quarter and couldn’t hold on, but the fighting spirit - typified by skipper Gary Caldwell, Alcaraz and Maynor Figueroa - ensured this time they could hold on.
Martinez had made one change to the side that was hammered against Arsenal, Alcaraz returning at centre-back for Steve Gohouri.
The Ivorian dropped to the bench in place of Adrian Lopez, with Shaun Maloney also named among the replacements at the expense of Albert Crusat.
As expected, the Baggies threw everything at Latics from the off, and could have been ahead inside three minutes.
Chris Brunt picked up the ball 25 yards from goal, and unleashed a super effort that Ali Al Habsi did well to tip on to the bar and over for a corner kick.
From the resulting set-piece, Jonas Olsson headed narrowly wide as Latics desperately tried to gain a foothold in the game.
Peter Odemwingie - a transfer target for Latics in the summer - and Shane Long were looking dangerous every time they got the ball as the home side pushed.
And the visitors needed a timely intervention from Caldwell to deny the Nigerian with the defence stretched.
Moses had gone into the game without a goal this season from 43 shots - the worst record in the top flight.
And his first effort was never going to threaten to end that record, flashing well wide of Foster’s goal.
Gomez picked up the first caution of the game midway through the half for gesturing an imaginary yellow card to the official after a rare Latics attack had been thwarted by the hand of Youssouf Mulumbu.
Mike Dean was perhaps correct to show Gomez a yellow, but quite why he failed to show one to Mulumbu for a clear yellow-card offence was baffling.
The referee further angered Wigan on the 25-minute mark when David Jones appeared to be fouled in the penalty area after good work from Moses and Conor Sammon, only for play to be waved on.
Odemwingie’s pace then had Caldwell backtracking, and Jerome Thomas’ shot was deflected over for the first of three Albion corners in a minute.
Al Habsi managed to clear the ball behind from the first, then Odemwingie saw a header catch a defender on the way past the post, with Alcaraz clearing the third to the relief of the away fans behind the goal.
West Brom then won themselves a free-kick on the edge of the Wigan box for a supposed foul by Caldwell on Long, the referee taking advice from the linesman some 40 yards away despite not having seen anything wrong from his own position barely 10 yards away.
And the feeling of injustice was exacerbated when Reid curled a magnificent free-kick over the wall and into the top corner, with Al Habsi rooted to the spot, 12 minutes before the break.
It could have gone either way at this point, Latics having ample reason to feel sorry for themselves and bemoaning another 50/50 call that had gone against them.
Fortunately they chose the other reaction, and it paid dividends within three minutes.
Momo Diame’s cross from the left was half-cleared by Mulumbu into the path of Moses, who smacked a beauty poast Foster into the far corner via the underside of the crossbar.
The rest of the half was end to end as neither side looked content to go in at the break all square, although both defences managed to adequately protect their goalkeepers.
The Baggies, predictably, started the second period with a bang, and slack play from Caldwell allowed Long to get his cross in, with Figueroa doing well to clear from the onrushing Brunt.
Reid then had his name taken for a late tackle on Moses, before a marauding run through the midfield from McCarthy was ended when he was tripped by Mulumbu on the edge of the area.
The Baggies’ midfielder protested his innocence, but he was soon glad that the official had stopped play as Gomez rifled a thunderbolt into the top corner that Foster wouldn’t have got near.
Jones’ free-kick was repelled by the wall, but Gomez wasn’t to be denied moments later when Moses was felled in the area by Reid and the Spaniard sent Foster the wrong way from the penalty spot.
With half an hour to defend their advantage, it was always going to require a determined defensive display to secure a second away win on the bounce.
But the initial signs were good as defensive trio Caldwell, Figueroa and Alcaraz stood tall to clear the first of what would surely be a wave of West Brom attacks.
Wigan hearts were in mouths on 63 minutes when Odemwingie went to ground after colliding with Al Habsi inside the box, although referee Dean saw nothing wrong.
And within seconds Sammon had made enough of a nuisance of himself to allow Moses a sight at goal, and his chip from 30 yards was only just clawed away by a back-peddling Foster.
That was the signal for Roy Hodgson to make his first change, Graham Dorrans for Mulumbu, the boos from the home fans showing what they thought of the decision to replace their favourite player.
Wigan also made two quickfire changes, Gohouri on for Alcaraz and James McArthur replacing Stam at right wing-back.
A diving save from Al Habsi to deny Long kept Wigan in front, and the goalkeeper then had to be at full stretch to tip away a searching cross from Nicky Shorey aimed towards the far post.
Latics wasted a golden opportunity to put the game to bed 15 minutes from time, Moses leading a wonderful counter-attack and successfully holding off James Morrison on the edge of the Baggies box.
But with Sammon unmarked to his right and screaming for a pass, the winger kept his down and his shot was blocked by one of three defenders standing between him and the goal.
The Baggies almost made them pay within a minute, Morrison’s cross being headed against the woodwork by Long, although the offside flag was up in any case.
Sammon then made way for Franco di Santo after another tremendous shift up top, and West Brom responded by sending on Somen Tchoyi for Odemwingie.
Figueroa got a priceless touch to a Thomas corner with Tchoyi waiting behind him to nod the ball home, while the home fans were up in arms when Tchoyi wanted to beat his man once too often in the area and was dispossessed after wasting a couple of clear chances to get a shot in.
Ex-Latic Paul Scharner appeared for the final five minutes as Hodgson played his last hand, Morrison the man to give way.
And the Austrian almost made his old club pay with his first touch, only for his bullet header from Thomas’ teasing cross to sail inches over the bar.
There was a major flashpoint on 88 minutes when Dorrans went to ground in the area after an innocuous-looking challenge from Jones.
But, with the home fans celebrating the apparent award of a penalty, Dean booked the Scot for simulation to the relief of everyone in the visitors’ ranks.
TV replays suggested the call could have gone either way but, having been on the wrong end of some rotten luck this season, Latics will feel they were owed the benefit of the doubt.
Caldwell then cleared the danger from another deep cross from Reid before, in the last of four added minutes, James McCarthy gave away a needless free-kick 25 yards out.
Thankfully, this Reid could only find the defensive wall and Dean’s whistle signalled scenes of jubilation in the away end and in the visiting technical area.
Latics: Al Habsi 7; Alcaraz 8, Caldwell 8, Figueroa 8; Stam 6, McCarthy 7, Diame 7, Jones 6; Gomez 7, Moses 8; Sammon 7.
Subs: Pollitt, Gohouri (for Alcaraz, 62) 7, McArthur (for Stam, 70) 7, Watson, Maloney, Di Santo (for Sammon, 80), Rodallega.
WBA: Foster; Reid, McAuley, Olsson, Shorey; Brunt, Morrison, Mulumbu, Thomas; Long, Odemwingie.
Subs: Fulop, Tchoyi (for Odemwingie, 81), Dorrans (for Mulumbu, 62), Dawson, Jones, Cox, Scharner (for Morrison, 85).
Referee: Mike Dean