Josh Murphy's first-half goal secured a 1-0 Fratton Park triumph to put the Blues seven points above the relegation zone.
On a day when so many of their relegation rivals also won, it made the triumph even more important from a match of few goal-scoring opportunities.
And here are our Pompey player ratings...
1. Nicolas Schmid - 7
Couldn’t do anything about Ohashi’s goal on the counter attacker and had little to do in terms of saves. But commanded his area well and took everything cleanly which came his way. Photo: Graham Hunt
2. Terry Devlin - 8
Strong first half, despite being beaten by Ohashi for the goal on the counter attack. Made a real niche for himself at right-back now and going to be extremely hard to dislodge amid fierce competition. Great late tackle on Gueye. Photo: Graham Hunt
3. Hayden Matthews - 8
(Replaced by Jordan Williams on 90 mins) Demonstrated a lot more aggression to his game and he put in his best performance of the season. Strong in the air, confident in possession and keen to drive forward. This was the Hayden Matthews of last term. Photo: Graham Hunt
4. Ibane Bowat - 8 - MOM
Unlikely match hero. Definitely improving with a run of games after his long injury lay-off, becoming more comfortable in his surroundings. More composed by the match, his 79th-minute header from Chaplin’s corner earned the points. Photo: Simon Roe