West Brom shrugged off Darren Moore's sending-off to record their first away win of the Premiership season thanks to Martin Albrechtsen's goal.
Moore was dismissed on 43 minutes after receiving his second yellow card for an unnecessary challenge on Jason Roberts.
But the Baggies took the lead on 56 minutes as Albrechtsen broke free and slid the ball under the keeper.
Wigan laid siege to the West Brom goal, with Tomasz Kuszczak making an amazing save from Roberts in injury time.
The game's first chance fell to West Brom's Steve Watson, but his acrobatic volley from a corner was straight at keeper Mike Pollitt.
Soon after, West Brom's Nathan Ellington hit the bar but the former Wigan striker had already been ruled offside - much to the delight of the home fans who booed his every touch.
Wigan struggled to find a cutting edge with Paul Scharner, Roberts and Graham Kavanagh all wasting good chances.
Moore picked up his first booking on 32 minutes for a clumsy challenge on Lee McCulloch, and was to pay the price later in the half.
West Brom were inches away from taking the lead on 34 minutes when Kevin Campbell got his foot to the ball as Pollitt and Stephane Henchoz hesitated.
Moore's sending-off was a clear-cut decision
As the game opened up, Moore was dismissed two minutes before the break after an ill-advised shoulder barge on Roberts.
The 31-year-old had no need to take Roberts out on the half-way line with plenty of covering defenders, but his blatant foul left the referee with no choice.
The Baggies made an immediate tactical switch, bringing on defender Albrechtsen for Ellington and the substitution paid unexpected dividends.
West Brom came out with all guns blazing for the start of the second half, and they deservedly took the lead through Albrechtsen's brilliant finish.
Ronnie Wallwork played the defender in and he showed all the goal-scoring instincts of a striker to slip the ball under Pollitt.
The goal finally woke Wigan up, and they attacked for the remainder of the match with McCulloch hitting the crossbar, from their first corner, on 62 minutes.
However, Albrechtsen made another excellent break from the half-way line and should have squared the ball for Darren Carter to make the game safe but greedily went for glory.
Wigan then hit back again and Pascal Chimbonda had two good chances with headers, while Kavanagh's 85th-minute free-kick drew an excellent save from Kuszczak.
The keeper repeated his heroics in injury time, though, with an incredible reaction save from Roberts to earn his side all three points.
Wigan boss Paul Jewell:
"We're very disappointed, but there's no panic.
"I've got players in mind that I want to bring in, but they might not be available at the moment.
"It wasn't about bad luck. We had loads of possession, but we didn't really test their goalkeeper until the end of the match."
West Brom assistant boss Nigel Pearson:
"You need everyone to contribute in games like this and Tomasz pulled off a marvellous save at the end.
"It's a situation you don't want to go through too often, but the players come out of it with a lot of credit.
"The circumstances asked questions of our character and belief and they can take a lot of positives from the game."
Wigan: Pollitt, Chimbonda, De Zeeuw, Henchoz, Baines (Johansson 80), Bullard, Kavanagh, Scharner, Teale, Roberts, McCulloch.
Subs Not Used: Filan, Jackson, Francis, Skoko.
West Brom: Kuszczak, Watson, Curtis Davies, Moore, Robinson,
Greening, Wallwork, Inamoto, Carter, Ellington (Albrechtsen 44), Campbell (Earnshaw 79).
Subs Not Used: Chaplow, Kirkland, Rob Davies.
Sent Off: Moore (43).
Booked: Wallwork, Moore, Robinson.
Goals: Albrechtsen 56.
Ref: M Atkinson (W Yorkshire).