The 20-year-old forward rounded off an incisive move to score his first goal of the season and provide the launchpad for a morale-boosting victory.
Rovers burst into a two-goal lead but their night became more complicated after an inexplicable error from Ian Lawlor allowed Portsmouth back into the game following the re-start.
Thankfully, on this occasion, Darren Ferguson’s men were not left licking their self-inflicted wounds. However, they were grateful for a last gasp redeeming save from Lawlor against the visitors’ ten men.
Rovers’ players had come into this game smarting from Saturday’s defeat at Charlton. They saw it as an opportunity missed to build momentum after spanking Southend.
They took that frustration out on Pompey in the best possible way by making a blistering start to the game, racing into a two-goal lead after just five minutes.
And, having scored the first goal, they looked a different team to the one so often this season that has found itself chasing games and ultimately running out of ideas. This time they had something to protect.
Rovers looked like a different team in another way too. They were without attacking trio John Marquis, Alfie May and James Coppinger, with Mandeville, Rodney Kongolo and Matty Blair stepping up. Niall Mason was dropped and Mathieu Baudry came in for this first appearance of the season.
It meant Doncaster adopted a 5-4-1 shape without the ball and 3-4-3 with it, and that alteration from 4-4-2 seemed to take the visitors somewhat by surprise.
Pompey had actually probed straight from the kick off but Rovers soon found space to play through the thirds and, in just the third minute, some neat work by Tommy Rowe released Kongolo down the right and his drilled cross was prodded home by Mandeville with the aid of a slight deflection.
How this Doncaster team has responded to scoring has been an issue this season. Too many times they have switched off and conceded immediately.
But this time it was textbook ‘going for the throat’ stuff as confidence soared and after five minutes they led 2-0.
Harry Toffolo’s deep corner from the left was headed back towards goal by Rowe and it went in courtesy of a bigger deflection off defender Matt Clarke.
Pompey were rattled.
Indeed they might have found themselves three down from another corner within 60 seconds only for the towering Andy Butler to head just wide, before they gradually clawed their way back into the game and went closest to scoring the game’s next goal.
Rovers, now with something to hold onto, closed down tenaciously and defended in an organised fashion, clearly boosted by the presence of Baudry.
They were thankful to the ever-impressive Joe Wright, though, for going in at the break with a two-goal cushion, the centre back positioning himself perfectly to clear a Ben Burgess header off the line after a free-kick to the back post.
The visitors started the second period on the front foot and substitute Conor Chaplin went close to halving the deficit when his free kick clipped the outside of the post.
Just moments later, however, Pompey were gifted a route back into the game when Lawlor inexplicably allowed Baudry’s back-pass from out wide to squirm under his feet and over the line.
The mood inside the Keepmoat Stadium switched to one of anxiety as Kenny Jackett’s side began to call the shots - only for Rovers to be given a helping hand on 69 minutes when eagle-eyed referee Martin Coy spotted an off-the-ball kick by Dion Donohue on substitute Niall Mason and had no hesitation producing a red card.
A nervy finish almost produced a final twist in stoppage time only for Lawlor to atone for his earlier error by producing a superb reflex save to keep out Jamal Lowe’s header from point blank range. The second half had been far from pretty but it was job done.
Rovers: Lawlor, Blair (Mason 46), Wright, Baudry (Beestin 72), Butler, Toffolo, Houghton, Whiteman, Kongolo, Rowe, Mandeville (Garratt 88). Subs not used: Marosi, Alcock, Ben Khemis, Fletcher.
Portsmouth: McGee, Thompson, Burgess, Clarke, Donohue, O’Keefe, Close, Evans (Lowe 46), Bennett (Chaplin 46), Kennedy, Hawkins. Subs not used: Bass, Oxlade-Chamberlain, Haunstrup, Naismith, Rose.
Referee: Martin Coy
Attendance: 7,211 (620)