A goal from Leon Clarke on his return to Wigan was enough to give his side all three points thanks to a 2-1 Sky Bet Championship victory over QPR at the DW Stadium.
Clarke was in the right place after 55 minutes to put Wigan 2-0 up, after Josh Windass had fired them ahead early on.
A nervy last 15 minutes was ensured when Bright Osayi-Samuel pulled one back with a deflected strike from distance.
But the home side were good value for the three points that increases the gap between them and the relegation dogfight.
Wigan almost made the worst start imaginable when Reece James was robbed of possession in centre-field, and the shot from Luke Freeman was spilled by Jamie Jones, who just about got up to smother the follow-up from Nahki Wells.
But the home side took full advantage of the let-off and went in front after eight minutes.
Clarke flicked on a long ball from goalkeeper Jones into the path of Windass, who took a touch and slid the ball past Joe Lumley with his left foot.
Jones was then in play at the other end when he had to race off his line to smother a shot from Wells, who had got the better of Cedric Kipre.
An unbelievable piece of skill from Anthony Pilkington then released Windass, who either did not see or ignored Clarke in the middle before it was too late.
Wigan deserved their slender interval lead, and the advantage was doubled within 10 minutes of the restart.
Michael Jacobs' cross from the left took a slight deflection and on-loan Sheffield United forward Clarke finished well at the far post, matching his tally during his half-season loan spell at the DW four years ago.
Pilkington almost made it three but was unable to turn in a James corner at the far post.
And a tense finale was ensured when Rangers pulled one back with 15 minutes to go, totally against the run of play.
Osayi-Samuel tried his luck from distance, and the ball took a massive deflection on its way past the wrong-footed Jones.
Wigan's unease was shown with them making three substitutions in as many minutes, but QPR were determined to make the most of their lifeline.
With the clock ticking down, Toni Leistner smashed the ball against the Wigan bar from 12 yards, with Jones getting nowhere near it.
And another Rangers break, which saw Matt Smith evade Kipre, was only ended when the Wigan defender tripped him on the edge of the box at the expense of a yellow card.
Freeman's free-kick hit the wall, but there was still time for Smith to beat Jones to a Wells cross, only for the ball to float harmlessly over the bar.
Paul Cook: "It's been a tough week for everyone, to lose a player with the character and stature of Will was hard to take. It was always going to have a massive effect on everyone - the supporters, the players, the management.
"He came in on Friday morning to say goodbye to everyone and it was a very emotional moment. He's been an absolute hero for this club, and if you'd have told me at 9-10pm on deadline day we were going to lose him, I'd have said not a chance.
"In fact we were working on bringing in another player, as well as Will, but unfortunately we didn't get that done and then we lose Will because of the money involved. I know there's been criticism of the owners and myself for allowing that to happen. But when you win football matches, everyone is suddenly happy again. We really needed the three points today, and I'm really delighted for the Wigan Athletic fans that we were able to deliver them."
Steve McClaren: "I feel hard done by, absolutely. Having said that, you can't concede two goals like we did and expect to win football matches away from home.
"The defence has been a key reason why we've been able to do what we've done this season, but in recent weeks we've lost the platform."