ISHMAEL Miller's third goal in six games should have counted for much more - but once again defensive errors cost Albion dear in an undeserved JJB Stadium defeat.
The Baggies opened the scoring two minutes after the break when Miller pounced on a Titus Bramble error to bag the club's first goal in 345 minutes of football.
Albion wasted several chances before Paul Robinson's weak back-header allowed Senegal hotshot Henri Camara to level just past the hour-mark.
The visitors continued to dominate, only to be denied time and again by ex-Hawthorns loan star Chris Kirkland.
And Tony Mowbray's men paid the ultimate price when Gianni Zuiverloon switched off at ex-Baggie Jason Koumas' 87th-minute corner to allow Emmerson Boyce to snatch all three points.
James Morrison returned from a knee injury to replace Do-heon Kim in the only change to Albion's starting XI.
Albion started brightly and could have gone ahead within two minutes when Morrison muscled his way past Bramble and Ryan Taylor before poking the ball across the six-yard box where Miller came close to getting a crucial touch.
Five minutes later, Camara should have put the hosts ahead when he got on the end of Emile Heskey's near-post flick-on from Taylor's left-wing corner but sent his five-yard volley well over.
Albion were at sixes and sevens in the 11th minute and Zuiverloon needed to be on hand to block Wilson Palacios' 20-yard strike.
Seconds later, at the other end, Zuiverloon got on the end of Jonathan Greening's left-wing cross but could not stretch far enough and sent his header way off target.
The Baggies pushed forward again in the 16th minute and this time Greening flashed a dangerous ball across the six-yard box which Boyce just managed to clip away before Miller could get a telling touch.
The visitors continued to press and, in the 21st minute, the impressive Greening won a free-kick which Chris Brunt fired just over from 30 yards.
A minute later, Greening latched onto a Brunt clearance down the left and cut inside Boyce, only to drill a left-footed strike high and wide when Miller was well-placed in front of goal for a simple tap-in.
The Latics were finding it difficult to get on the ball but Antonio Valencia broke well down the right in the 31st minute and crossed for Heskey, who headed wide of the near-post from 12 yards.
However, it was the Baggies who threatened again two minutes later when Abdoulaye Meite should have at least headed Brunt's right-wing corner on target but unwittingly played a one-two with the Northern Ireland international!
Five minutes before the break, Meite gave away a needless free-kick when he handled.
Taylor curled the resulting set piece around the wall and towards the bottom right-hand corner, but Scott Carson did well to get down and turn the ball around the post for a corner.
The Baggies came flying out of the blocks after the break and snatched a 47th-minute lead.
Wigan did not look in trouble when Boyce squared the ball to Bramble at the back.
But the ex-Newcastle centre-half turned into danger and Miller stole the ball before easing into the box and coolly sliding past Kirkland and just inside the left-hand post.
Four minutes later, Miller's flick-on from the immaculate Robert Koren's ball put Morrison in the clear, only for the Scotland international to see Kirkland block his low shot with his feet.
Wigan threatened briefly when Taylor flashed another free-kick inches past the left-hand post.
Albion were soon back on the attack when Koren and Greening combined well to slot Brunt through on goal.
The former Sheffield Wednesday midfielder carried the ball into the box before seeing his right-footed effort well saved by Kirkland.
From the resulting Brunt flag-kick, Paul Robinson sent his near-post header over the bar.
On the hour-mark, Valero got to the right by-line and cut the ball back for Miller, whose goalbound strike was well blocked by Boyce.
How Albion would rue those missed chances.
Bruce made a change when Koumas, who was roundly booed by the Baggies' huge following, came on for Michael Brown.
Albion gifted the Latics an equaliser in the 61st minute when ex-Wolves striker Camara pounced on Robinson's weak back header and spectacularly volleyed past Carson from eight yards.
The Baggies regrouped and, two minutes later, Brunt crossed from the left and Greening raced in at the back post but fired wide from a difficult angle.
Brunt did well again in the 68th minute when he centred from the left by-line for Valero, whose 15-yard header lacked the power and accuracy to beat Kirkland.
Kirkland had to be at his best again in the 75th minute when he somehow parried Jonas Olsson's point-blank header from Brunt's right-wing corner.
Robinson managed to get to the rebound first but, under pressure, put it over.
Brunt's 80th-minute corner was pushed out to Greening, who drilled it back in, only for Kirkland to produce another fine save.
Wigan responded when Lee Cattermole struck a 20-yard shot straight at Carson before Heskey headed a Koumas centre wide.
But the Latics punished the Baggies three minutes from time when Zuiverloon lost Boyce at a Koumas corner, allowing the ex-Crystal Palace defender all the time in the world to plant a stunning header inside the top left-hand corner.
Albion looked devastated but managed to launch a desperate last effort to bag a point.
After pegging the hosts back for the rest of the game, the Baggies knew their luck was well and truly out when Greening saw a 93rd-minute exocet from the edge of the box beat Kirkland and fly inches over.
WIGAN (4-4-2): Kirkland; Taylor (Melchiot 70), Bramble, Boyce, Figueroa (Kilbane 81); Valencia, Cattermole, Brown (Koumas 60), Palacios; Camara, Heskey. Subs not used: Pollitt (gk), Kingson (gk), de Ridder, Cywka.
ALBION (4-5-1): Carson; Zuiverloon, Meite, Olsson, Robinson; Morrison (Moore 89), Valero, Koren, Greening, Brunt (Bednar 89); Miller. Subs not used: Kiely (gk), Teixeira, Barnett, Kim, Cech.
GOALS: WIGAN - Camara (61), Boyce (87). ALBION - Miller (47).
BOOKINGS: ALBION - Miller (over-celebrating 48), Greening (foul 86).
REFEREE: P Dowd (Staffordshire).
ATTENDANCE: 17,054.
ALBION STARMAN: Robert Koren.
PIC: ON TARGET...Goalscorer Miller battles with Bramble
