Ibane Bowat's second-half goal was enough to lead Portsmouth to a vital 1-0 win at home to relegation rivals Leicester as the Foxes plunged a huge step closer to League One.
Substitute Bowat's scruffy 63rd-minute strike from a corner earned Pompey a third straight win to leave them on the cusp of safety.
It is now one win in 17 for the hapless Foxes, whose demotion to the third tier 10 years after winning the Premier League could be confirmed as soon as Tuesday night.
Pompey welcomed back Conor Chaplin after he was ineligible to face former club Ipswich in mid-week while Keshi Anderson also came back into the starting XI.
Leicester recalled veteran goalkeeper Asmir Begovic against his former club along with Hamza Choudhury and Bobby De Cordova Reid.
The Foxes could have had a penalty early on when Patson Daka appeared to be caught by Conor Shaughnessy but referee Gavin Ward waved away their appeals.
For a team rooted in the bottom three, Leicester showed a bizarre lack of fight throughout and it took until the final seconds of a dour first half for De Cordova Reid to muster the first shot on target from either team.
De Cordova Reid's shot from a tight angle was never going to seriously trouble home goalkeeper Nicolas Schmid.
Portsmouth started the second half on the front foot and had a good chance when Millenic Alli rounded Begovic but could only carry the ball harmlessly out for a goal kick.
Adrian Segecic also missed a golden opportunity when he blazed wide after racing onto Colby Bishop's brilliant knockdown.
Pompey broke the deadlock in the 63rd minute when a Segecic corner caused havoc inside the Leicester penalty area and Bowat got the last touch of three Pompey players that crowded the left side of the six yard box at the far post.
Choudhury managed to get himself booked for inciting the crowd as he left the pitch after being substituted but, on the pitch, the Foxes offered next to no fight.
Pompey defender Regan Poole put himself on the line to block a Daka shot and celebrated like he had scored the winning goal.
Daka then picked up a booking for a needless late challenge on Schmid as he chased down a back pass.
Substitute Divine Mukasa fired a 40-yard free-kick wide in stoppage time as the home fans celebrated, knowing their team are virtually guaranteed survival.
Leicester meanwhile need a miracle after a run of one wins in 11 under manager Gary Rowett.
Portsmouth's John Mousinho:
"This does feel like a massive step to safety as we are 10 points ahead of Leicester now.
"We are a little bit disappointed with the performance and it wasn't a very good game of football, not one for the purists, but we deserved the win.
"I know the home fans don't care. It was just one of those games with the injuries early on it was so disrupted. The first half was stop-start and there was hardly any football played.
"The goal summed up the game to be honest, a scrappy winner that we squeezed in at the back post.
"It is absolutely huge for us. We needed to give ourselves something because of the games we've got coming up, and how difficult everything is at this stage of the season.
"This run will define the season and it's good that Leicester are one of the sides that cannot catch us."
Leicester's Gary Rowett:
"It is disappointing and I think it's been rinse and repeat of what I've said after the last five games.
"It was a very physical game and Portsmouth made it very difficult. They want to smother you. I thought we actually dealt with it okay and I didn't think there was much in the game.
"I think a lack of fight is something that's been labelled at the team over the course of a season. I don't know whether that's fair but I think we showed a lack of quality.
"I thought we showed a lack of composure. I thought we showed a lack of toughness to do the basics in the one moment where we concede from a set-piece.
"I can say we've got belief. I think we have to show that in our performance and show that in our results."
