The Blues had two-goal left-back Lee Brown to thank as they picked up an excellent 3-1 win over AFC Wimbledon.
And with Charlton drawing to Accrington it means the fate of Danny Cowley’s side is back in their hands with a game to go.
Victory over Accrington in their final game and a place in the play-offs is assured.
Cowley’s men were good value for their victory on the club’s first visit to the new Plough Lane.
But there were some hairy moments with the Blues controversially falling behind before smashing in three goals in a breathless first 45 minutes.
Pompey were on the back foot from kick-off with their defence looking shaky.
There was controversy about Wimbledon’s opener, though, with Joe Pigott miles offside as the ball came forward, before his fired home.
Ref Charles Breakspear ruled the ball had come off Ben Close, although it appeared Ben Heneghan initially played it forward.
Pompey were level seconds later, though, with the lively Marcus Harness the architect as he drove forward and crossed for Curtis to finish inside the box.
Inspiration arrived from the most unlikely of sources in stoppage time as Brown sensationally helped himself to two goals.
First a lovely flowing move involving Ryan Williams and Curtis finished with the left-back lashing him an angled drive.
Then it got even better as Tom Naylor won the ball by the Pompey box, Williams powered forward and Curtis found Brown who coolly fired into the roof of the net.
Two quickfire openings arrived after 61 minutes as first Marquis tried to take a touch from Harness’ ball when he should’ve shot. Then the ball dropped to Brown at a tight angle who opted for a pass when he could’ve shot on a hat-trick and the home side dealt with the threat.
Pigott and sub Ayoub Assal then both had sights of goal to warn the visitors the home side were still a threat.
Marquis then missed a one-on-one with five minutes remaining and another chance at the death but it mattered little on a fantastic afternoon for the Blues.