Pompey Academy were unable to make the most of their chances as they were beaten 2-1 at Yeovil in Merit League One.
The visitors controlled long periods of the contest, but a goal in each half from Devon Arnold put their opponents in control.
Harrison Brook volleyed home an Oscar Johnston cross to reduce the deficit, but the Blues were unable to find a leveller.
Academy manager Mark Kelly said: “The start was really sloppy and we found ourselves a goal down early on.
“We managed to get ourselves back into the game and had some good opportunities to level before the break that we just couldn’t take.
“We told the lads to get the ball moving more and that’s exactly what they did – there were probably around 10 excellent chances for us to score.
"I was pleased with the way we went about things in the second half and there are positives for us to take."
“Alfie Stanley had a couple of one-on-ones and on another day, he would have got a hat-trick, but he just needs to keep plugging away.
“We were in total control at that point, but Petar Durin made the wrong decision with a kick out and their lad nipped in to find the net.
“It was a nice finish from Harrison following some great build-up play from Alfie and Charlie Bell, while their keeper then pulled off some great saves.
“I was pleased with the way we went about things in the second half and there are positives for us to take, although it’s obviously disappointing that we weren’t clinical enough to get a result.
“We’ve got a few injuries at the moment, so some of the under-16s came and played some neat, clever football, which was particularly pleasing.”
Pompey: Durin; Hancott, Mnoga, Bruce, Flint; Whiting, Bell; Johnston, Lee (Brook 52), Teggart; Stanley