A third successive League One victory sent Pompey to the top of the early season standings.
Ryan Tunnicliffe combined well with Marcus Harness to score the only goal of the game against Shrewsbury after just 120 seconds.
It was an outcome very much welcomed by the noisy crowd inside Fratton Park, but Danny Cowley wants more.
While the result was pleasing, he knows his side need to perform better if they are to continue their winning run.
The Blues boss said: “It was a really good goal from our perspective and a great interchange between Ryan and Marcus.
“We had control in the first half, but didn’t play with enough purpose and then your attackers lose their positional discipline. You become less of a threat at the top end of the pitch.
“Credit to Shrewsbury because they were direct and physical, and made it very tough for us. They asked a lot of questions.
“You look at League One and nobody has won by more than a single goal tonight, which shows you how tight the division is. There’s not a lot between the teams.
"We’re pleased to win and keep accumulating points, although there’s a lot of learning for us and plenty to improve on."
“But we want to play better than that and with more rhythm. We certainly want to see games out better than we did.
“The positive was another clean sheet, though, and we defended our box well – Sean Raggett was immense.
“Gavin Bazunu did what top goalkeepers do – he hardly had a shot to save, but when called upon made a brilliant stop late on.
“We’re pleased to win and keep accumulating points, although there’s a lot of learning for us and plenty to improve on.”
Pompey were forced to bring off both Harness and skipper Clark Robertson before the second half began.
Cowley said: “It wasn’t easy for us to lose two players to injuries at the break – it was an impact one for Marcus on his quad. We’ll know more in 24-48 hours.
“We thought it would be okay for Clark to continue, but we sent him out early after the break and it just wasn’t right.
“His ankle has just ballooned up after a collision. It’s settled somewhat since, though, and we’ll keep our fingers crossed.”