Pompey Academy began the new Youth Alliance season with a 1-0 defeat to Yeovil at Copnor Road.
The hosts created plenty of chances, but were made to pay for their profligacy when a mistake at the back led to the game’s only goal.
Josh Flint had a shot saved, while Stan Bridgman was unable to find the target with a close-range header.
It was a similar story for Haji Mnoga later in the first half, while Bridgman and Leon Maloney also failed to make the most of promising opportunities.
Yeovil took advantage of those let-offs by taking the lead soon after the restart, with goalkeeper Leon Pitman failing to get to the ball after coming from his line, allowing Dan Nield to score.
Maloney had the best chance to secure a share of the spoils, but his goalbound effort was hooked from the line.
Academy manager Mark Kelly said: “It was an entertaining, free-flowing game and we got in behind them a lot in the first half.
“Harry Kavanagh did well down the right-hand side and there were plenty of balls across the face of goal, but we couldn’t get on the end of them.
"It’s disappointing that one mistake and not taking our chances has cost us."
“We missed quite a few chances that should have been put away and the second half was more of an even contest.
“It was a bad mistake from our keeper for the goal. He came out and got nowhere near the ball when he should have stayed back.
“We were chasing the game after that and were perhaps a bit to anxious, although we should have been awarded a penalty and Leon’s shot was cleared off the line.
“There was a lot of pressure from us, but we were lacking that clinical instinct. It’s disappointing that one mistake and not taking our chances has cost us.
“Now there is plenty for us to work on in training, particularly in the final third. We need to get crosses into the box sooner and try to improve our finishing.”
Pompey: Pitman; Dandy, Mnoga, Robb, Kelly; Kavanagh (Brook 60), Read, Whiting (Stanley 51), Flint (Rew 60); Bridgman, Maloney