Pompey Academy were beaten 2-0 by Northampton in a Youth Alliance Cup tie.
Jack Daldy’s brace ensured the Blues exited the competition in the first round at Wellingborough’s Dog & Duck ground.
Academy manager Mark Kelly said: “It turned out to be a very frustrating game from our point of view.
“We were excellent from box to box and a had a lot of control over the game, playing some really nice football at times.
“There were a lot of occasions when we got in behind our opponents, but we were lacking a cutting edge.
"Now we need to raise the quality and belief levels, so we’ve got some work to do on the training ground."
“A lot of deliveries went straight to their keeper and we have to learn to be more aggressive with balls into the box, while also finding a ruthless streak in the final third.
“It was disappointing that we gave away two sloppy goals. The first was from a free-kick that came back off the wall and we didn’t react quickly enough, while we were caught in possession for the second.
“Our concentration levels need to improve, but I can’t fault the attitude of the boys or some of the football they played.
“Now we need to raise the quality and belief levels, so we’ve got some work to do on the training ground to try to put things right.”
Pompey: Pitman; Mnoga (Rew 36), Dandy, Robb; Kavanagh (Bruce 52), Kelly (Flint 52), Read, Whiting, Maloney; Stanley (Johnston 65), Lethbridge (Bridgman 71)