Josh Windass scored the only goal 16 minutes from time to give Wigan a thoroughly deserved 1-0 victory over Sky Bet Championship high-flyers West Brom.
It was a losing return to the DW Stadium for Baggies assistant manager Graeme Jones, who was Roberto Martinez's No 2 when Wigan lifted the FA Cup in 2013.
But the visitors can have few complaints having been second best for much of a fiercely-competitive encounter at the DW Stadium.
And any chance they had of getting back into it late on was ruined by the dismissal of Jake Livermore for a second bookable offence with six minutes remaining.
West Brom started the brighter, and they might have led had Jay Rodriguez not planted a header from Craig Dawson's cross straight at Christian Walton.
At the other end, Wigan threatened when Gary Roberts - one of four changes to the starting line-up following the 4-0 drubbing at Preston before the international break - sent over a wonderful cross that
only just eluded three team-mates.
Windass found himself through only to chip well wide of the far post, with only goalkeeper Sam Johnstone to beat.
Wigan thought they had won a penalty just before half-time when Nick Powell was tripped right on the edge of the box.
But referee Jeremy Simpson ruled it was an inch outside, and Powell lashed his effort into the Baggies wall.
Roberts fired just wide before the half-time whistle, and Wigan were almost made to pay for their profligacy at the start of the second period when Harvey Barnes raced into the box.
The exciting youngster took a tumble and Simpson immediately blew his whistle - only to book the West Brom man for diving and award Wigan a free-kick.
Windass was enjoying arguably his best game for Wigan, and he saw a shot brilliantly saved by Johnstone before he did break the deadlock 16 minutes from time.
The former Rangers man raced through the right channel before smashing a low shot into the bottom corner that Johnstone could not get near.
Wigan continued to push and came close to doubling their lead moments later.
Roberts sent over a fine cross from the right, which had centre-back Chey Dunkley's name all over it.
However, at the last second, Powell strained to get his head on to the ball, and succeeded only in flicking it out for a goal kick.
West Brom's cause was not helped when Livermore was given a second yellow card with six minutes to go for fouling Windass, who had forced the mistake with tireless running.
And the home side were able to see out the five added minutes to record a first win in four matches.
Paul Cook: "I was just pleased with the performance first and foremost. No matter how a game goes, as a manager you're far more interested in how your team performs.
"On the back of the international break - and our worst performance under me at Preston a fortnight ago - the lads have shown what they're all about. We've bounced back excellently and I thought we played well, everything about us. The lads who came in to the team were excellent and I'm delighted with the win."
Darren Moore: "We've all seen the Championship for long enough to know those sort of games are lying in wait for you and I've got absolutely no complaints on the day.
"It was a game where both teams were battling, not much goal action, whatever chances there were it was all off target. I just think you have to give Wigan credit for the way they played and their game plan. We tried to come here and win a game, they tried to win the game, and the ball's fallen to their lad once - and it didn't for us."