A penalty from Brett Pitman and a second-half strike from Jamal Lowe handed Portsmouth a 2-1 win over promotion-chasing Wigan at Fratton Park to boost their play-off chances.
Pitman rattled in a penalty just before half-time after Dan Burn was penalised for a foul on Ben Close, before Lowe doubled Portsmouth's lead 10 minutes after the interval with a good turn and finish.
Substitute Will Grigg set-up a nervy finale by scoring in the 89th minute for the visitors but Portsmouth stood firm to hang onto an invaluable victory.
The result moves Portsmouth up into seventh place in the table - level on points with Peterborough and Charlton above them - while Wigan remain in third, albeit with games in hand over Blackburn and Shrewsbury in first and second.
Wigan struggled to carve out too many clear openings in the first half but they did have a decent shout for a penalty waved away when Nick Powell's free-kick looked to be handled by a couple of Portsmouth players in the wall.
Instead, it was Portsmouth who were awarded a spot-kick and Wigan had complaints over that decision too. Burn stretched out one of his long legs on the edge of the box and Close seemed content to go over it. There could be no complaints about the penalty itself, though, as Pitman finished it emphatically to the left, sending Christian Walton the wrong way.
Wigan continued to look jaded at the start of the second half and they soon found themselves 2-0 down. Portsmouth worked it well with Nathan Thompson sending a cross into Lowe's path and the winger skilfully evaded the attentions of Burn with a neat turn before confidently dispatching a shot past Walton on his weaker left foot.
Even after that goal, it took a while for Wigan to inject any real urgency into their play. With just over 20 minutes remaining, Nick Powell had their best moment of the game when he waltzed away from a couple of challenges by Jack Whatmough and Matthew Clarke, only to see his low shot destined for the corner diverted onto the crossbar by Luke McGee's outstretched foot.
Paul Cook, returning to Fratton Park for the first time since switching Portsmouth for Wigan last summer, threw on Ryan Colclough, Gary Roberts and Grigg in search of a route back into the game and the latter almost provided some inspiration when his instinctive volley from close-range drew an excellent reaction stop from McGee.
Grigg needed no second invitation to get the better of McGee, though, powerfully heading beyond him with a minute of normal time remaining after ex-Portsmouth fan favourite Roberts had picked him out and despite sending goalkeeper Walton up in the dying stages in search of an equaliser, Wigan ended up on the losing side.
Man of the match - Gareth Evans
It was a gutsy, determined performance from Portsmouth and no player epitomised their attitude more than Gareth Evans in midfield - he was absolutely everywhere.
Alongside his cohorts Anton Walkes and Ben Close, Evans managed to keep arguably the division's best player Nick Powell relatively quiet while he was combative and authoritative throughout.
His desire to help Portsmouth get over the line was further emphasised when he somehow managed to carry on after Jack Whatmough had smashed a clearance onto his head from point-blank range.
The managers
Kenny Jackett: "It was a big win considering the circumstances where we are still chasing the top six. It was the fourth win on the trot and gives us a great run at the right time. Wigan are a very good team and I felt their pressure came on from about 60 minutes. We had to make sure we stuck to our game plan and didn't try to press them too deep.
"To get two goals against a team like this is a really big thing. The win keeps our season alive. Congratulations to them, they have got 23 clean sheets out of 38 games which is why they are where they are."
Paul Cook: "The penalty decision is a big decision. We felt we might have had a penalty in the first half ourselves. But that's part and parcel of the game. We really thought we could come here, play well, win the game and stamp a bit of authority on the division, but it wasn't to be.
"It's just another game, we've got another eight to go, and there'll be more twists and turns ahead. That's the nature of football, and you just keep going until the end of the season."
What's next?
Portsmouth travel to struggling to Rochdale next Saturday while Wigan will be looking to continue their promotion push with a win at home to MK Dons.