Pompey Academy were beaten 2-1 by Gillingham in their latest Merit League contest at Copnor Road.
Goals from Elliott Moore and Sam Gale ensured the visitors enjoyed a healthy advantage at the interval.
Alfie Bridgman (pictured) fired home a free-kick to reduce the deficit, but the Blues could not find a leveller.
Professional development phase coach Liam Daish said: “It was an even encounter in the first half and we just defended poorly in two moments, which our opponents capitalised on.
“Gillingham are a big, physical side and we tried to play through them, when we needed to get around them and send crosses into the box.
“It wasn’t a fair reflection of the game that we were trailing by two goals at the break, but then we started to utilise our strengths.
"They rode their luck at times, although the story of the game was that they took their opportunities and we weren’t clinical enough."
“We were able to get our wing-backs into play more and start to cause a few problems, with Alfie’s free-kick getting us back into the contest.
“And from that point on, we looked like the side who were more likely to go on and score further goals.
“Jamie Howell and Elliott Simpson both had good chances to level, but we couldn’t convert them and that gave Gillingham hope that it was going to be their day.
“They rode their luck at times, although the story of the game was that they took their opportunities and we weren’t clinical enough.
“I really couldn’t fault the effort from the lads and it was just about taking a little more care in the final third.
“One big positive was that we had seven 16-year-olds in the squad. They equipped themselves well and would have learnt an awful lot.”
Pompey: Steward; Kaba, Fox, Laidlaw; Trialist 1 (Kamavuako 67), Aston, Trialist 2 (Hurst 83), Simpson (Bosaka 75), Bridgman; Trialist 3, Howell