Pompey made it a second win in the capital within a week, following an outstanding performance at high-flying Millwall.
The match at The Den was goalless at the break, but 20 seconds after the restart Gustavo Caballero’s stunning finish from the angle opened the scoring.
John Swift finished off Millenic Alli’s pull-back to make it 2-0, before Casper De Norre pulled one back on 64 minutes.
However, skipper Marlon Pack rifled home a third to complete a 3-1 victory and provide a six-point cushion above the Championship relegation zone.
And here are our Pompey player ratings...
9. Millenic Alli - 8
(Replaced by Ibane Bowat on 90 mins) Really up and down against Millwall, but remained a constant threat on the left wing with his pace and directness. Sure enough, his charge into the box laid on a 55th-minute goal for Swift. | Graham Hunt/ProSportsImages
10. John Swift - 8
(Replaced by Adrian Segecic on 70 mons) Brilliant work from Alli teed him up for a first-time right-footed finish for Pompey’s second on 55 minutes. Looked a bit leggy at times and careless in possession, but his positive impact at present is huge. | Graham Hunt/ProSportsImages
11. Gustavo Caballero - 9 - MOM
(Replaced by Jacob Brown on 85 mins) A new hero is born. Great early sliding tackle outside Pompey’s box and then had Blues’ first chance with a shot pushed out by Millwall’s keeper. But better was to come with a stunning finish from a tight angle to open the scoring 20 seconds into the half. Not afraid to mix it either. | PA
12. Colby Bishop - 7
Had an involvement in Pompey’s opener when he appeared to be fouled after flicking the ball on, with Caballero exploiting the space to score. Wasted one glorious chance at the end of the first half. Battled away but little reward. | PA