Kenny Jackett wants to see his players making the most of their attacking talents.
Pompey created plenty of scoring chances in their pre-season friendly against League Two side Stevenage.
Gareth Evans and Conor Chaplin took two of them, but plenty more openings were squandered at Broadhall Way.
Boro struck three times – with Andronicos Georgiou’s brace adding to a Ben Kennedy strike – between those goals for the visitors to end up with the win.
And Jackett knows that Pompey cannot afford to be so profligate when the competitive action begins next month.
"The way we attacked was positive and we looked a threat, but then we have to try to do more damage."
The Blues boss said: “We got the ball into their box and had a lot of chances, with quite a few headers during the second half.
“So we really have to do better and make sure we put those away because too many were going over and wide.
“Both wingers were unlucky not to score after getting into good positions – both Ronan and Jamal had a high number of chances throughout the game.
“The way we attacked was positive and we looked a threat, but then we have to try to do more damage.
“We could have had a hatful and so the players have to work towards hitting top form for that Luton game in a few weeks.
“We’re disappointed to lose – as always – because we want to build up some winning momentum, but we’ve learnt a lot.
“I felt we were a bit brittle at the back and we want to be stronger, making sure not to give away those goals.”