Mark Kelly was proud of his young Blues, despite an FA Youth Cup exit to Leicester at Fratton Park.
Pompey took the lead with a Dan Smith spot-kick, only for Kairo Edwards-John to hit back for the higher-ranked Foxes early in the second half.
And the same player then grabbed a winner in extra-time, to bring the hosts’ run in the competition to an end.
Kelly was pleased with how his charges performed in the third round contest and just felt they were lacking a clinical edge.
Pompey’s academy manager said: “It was a good finish from Dan with the penalty and there were plenty of really encouraging displays all over the pitch.
“We started too slowly in the second half, though, and that allowed Leicester to come out and get the equaliser.
"We were just missing that level of finishing to be able to finish the tie off."
“But to be fair to our lads, we stabilised again and probably should have ended up with two or three goals.
“You have to deal with conceding in football and from that point we found good patterns of play and got into the final third a lot.
“We were just missing that level of finishing to be able to see the tie off, so the boys are disappointed.
“What you do in the box is ultimately what wins games of football and there were a few chances that we’d no doubt be putting away on a Saturday morning.
“The goal that won the game for Leicester was a real bit of quality and that was ultimately what was missing for us.
“But I think that they came off the pitch at the end knowing that they had been involved in a proper game of football. It could have gone either way.
“Our lads have worked brilliantly and we knew the style that we wanted. They approached things excellently.
“I’m proud because they were never on the back foot. They stood up and quite a few of them really impressed.”