It was a more comfortable victory than the final scoreline might have suggested.
A Brett Pitman penalty was followed by goals from Omar Bogle and Viv Solomon-Otabor, as Pompey raced into a three-goal lead at Walsall.
Jon Guthrie converted a couple of late goals – the second of which came deep into stoppage-time – to ensure the outcome was closer than it might have been.
Kenny Jackett was unhappy that they were allowed to stand, but pleased with the way his side performed at the Bescot Stadium.
The Blues boss said: “I really did think that our attacking players were a real threat and they got us the goals that won the game.
“I’d been looking for the right combinations in those number nine and 10 positions. Brett has worked hard to get back into the team in a slightly deeper role.
“When you’ve got a pacier forward – and we saw that from Omar with the second goal – he can use his experience to link play, while there was nobody better to take that penalty.
"I’d been looking for the right combinations in those number nine and 10 positions."
“It was a competitive game on a tricky pitch and a totally different encounter to the Charlton one at the weekend.
“When Walsall did attack, we had to be able to counter-attack quickly and we I felt did that in both halves.
“It was a difficult end to the match, with goals conceded from two set-pieces. They were just wrestling our players inside the box and it was worth the gamble for them.
“There was nothing we could do about it and, perhaps because we’d been given a penalty earlier, it was never going to be a foul the other way.
“You’re never happy as a manager until you hear that whistle blow, so we needed to come through that and ultimately we did.
“Overall I felt we looked a good team and applied ourselves well to get a very good win after the disappointment of Saturday.”
Pompey were without Ronan Curtis after the Republic of Ireland suffered a freak injury earlier in the day.
Jackett explained: “He had a nasty accident in the morning when he caught his finger in a door and it’s pretty nasty.
“It could be some time out because it’s quite serious. He’s had some surgery and I’ve seen the pictures – it looks quite gruesome.
“We’ll have to see how he is and hope he’ll be okay, but he certainly won’t be back for Saturday. It’s a very sensitive area.”