Pompey spent the closing stages throwing the kitchen sink at Shrewsbury in search of a winner.
But John Mousinho wants to see his side have that attacking intent on display from the start of games.
They fell behind to Rob Street’s header early in the second half before Marlon Pack nodded home the equaliser.
A late red card for Tom Flanagan gave the visitors an added boost, but they were unable to score again.
And Mousinho knows that Pompey cannot afford to wait until conceding before they hit their offensive stride.
The Blues boss said: “It’s a disappointing one – not just the result, but also the performance, which wasn’t up to scratch.
“In the end we’ve come away with what we deserved because there was a lot of endeavour, but we didn’t show enough quality in possession when we were in the final third.
“I know that we’ve got players on the pitch who can do that – we’ve seen it over the past 10-12 weeks.
“Something we have to work on as a coaching unit and a team is that we didn’t come alive until going 1-0 down.
“I know that Shrewsbury dropped off naturally, but we also stepped up a couple of notches and we have do it from the start.
"We’ve come away with what we deserved because there was a lot of endeavour, but we didn’t show enough quality in possession when we were in the final third."
“You can’t just look to stay in the game and wait for something to happen, although we could have won it in the end.
“We haven’t been properly punished and we’re in still sight of sixth, but I think we’ll rue the opportunities we’ve missed over the past few matches.”
Mousinho felt that Pompey were unfortunate not to be awarded a spot-kick on a couple of occasions.
He said: “There were two really strong penalty shouts – the first on Reeco when the defender hauled him down and that’s given anywhere else on the pitch.
“The other one is on Connor and Chey Dunkley is late on him. The explanation from the fourth official is that there’s momentum and there will always be contact after the ball goes away.
“My reply to him was that’s exactly what a foul is – and it’s what Marlon was booked for in the first half.
“Because it’s in a box there seems to be a much higher threshold for decisions, but a there shouldn’t be.
“We can’t come away blaming the officials for why we haven’t won, though, because we have to do more to make sure we’re not relying on those moments.”
Mousinho also allayed fears over the fitness of midfielder Tom Lowery, who was absent for the trip to Shropshire.
He said: “Tom picked up a slight knock in training on Thursday and he probably won’t be available on Tuesday night, but it’s not a long-term one.”