Conor Chaplin registered a priceless last-gasp goal as Pompey performed a smash and grab at Middlesbrough.
The Blues manfully defended their penalty area for much of the game, particularly in the second half, to keep the promotion-hunting Boro at bay.
Then, in seven minutes of stoppage time, Marlon Pack’s corner was picked up by Adrian Segecic and his shot deflected off Chaplin into the net for a 1-0 victory.
John Mousinho’s men had set to drop into the relegation zone, instead a late, late win keeps them in 21st spot.
Here are Pompey’s player ratings…
5. Madiodio Dia - 8
(Replaced by Conor Shaughnessy on 85 mins) Back in the team again to protect Shaughnessy for Tuesday night’s game against Ipswich and produced his best Pompey game yet. Strong, physical and grew in confidence as the match wore on. Important double block in the first half. | Simon Roe/ProSportsImages
6. Jordan Williams -8
(Replaced by Ibane Bowat on 75 mins) Answered the Blues' left-back crisis for his first start in three-and-a-half months and another sterling effort after his Oxford showing. Booked on 26 minutes, but didn’t let that effect him as he knuckled down and put in a determined display, | Graham Hunt/ProSportsImages
7. Marlon Pack - 8
Another incredible shift from the skipper, who looked absolutely shattered at the end and understandably so. Put his heart and soul into the display during a tough second half, especially. | Jez Tighe/ProSportsImages
8. Andre Dozzell - 8
Great to have him back in the side after his recent injury layout, gives Pompey so much. Headed Hansen’s shot off the line at the death in a vital intervention. | Graham Hunt/ProSportsImages