Pompey conceded a controversial goal as they slipped to a 2-1 Youth Alliance League defeat at Forest Green.
They were coping well with the hosts’ direct style and came close to forging ahead, only for Alfie Stanley to send a shot agonisingly wide.
But Destiny Oladipo and Taylor Marsh netted in quick succession late in the second half to hand Rovers the initiative.
The Blues were incensed that the first was allowed to stand, however, with the referee failing to spot a clear handball.
There was at least a consolation when Liam Kelly’s volley was cleared from the line and Harrison Brook clipped a cross back into the box for Stanley to nod home.
Academy manager Mark Kelly said: “It was an interesting game because our opponents basically played with a front five and just looked to punt the ball into our half.
“They had a goalkeeper with a long kick and weren’t interested in getting it down and playing football, so we had to keep our shape and look to build.
“But our back four and Joe Ridley in goal were superb, mopping everything up and allowing us to get into the game.
“We had some wonderful opportunities to score and Alfie probably had the best when he went through one-on-one, but poked his shot an inch wide. That might have killed Forest Green off.
“The two under-16 lads Charlie Bell and Harrison also got into decent positions and perhaps needed to pull the trigger a bit earlier, but that’s the difference when you step up a level.
"Everyone stopped, but the referee gave the goal. He apologised afterwards and said he thought it was a header, but then the reaction from both sides told him it wasn’t."
“We were in control and looking to win, but then the ball gets pumped into our box and their lad palms it into the net.
“Everyone stopped, but the referee gave the goal. He apologised afterwards and said he thought it was a header, but then the reaction from both sides told him it wasn’t.
“I’m not sure why he couldn’t then overturn the decision. It really was a blatant handball and a real kick in the teeth.
“Our heads went down and we switched off from a free-kick, which they capitalised on to score. The lads need to learn that decisions can go against you and it’s important to regain control quickly.
“We pulled one back and it was all us in the closing stages, but we couldn’t find another goal and the lads were gutted afterwards.
“It was disappointing because we deserved to win and instead came away with nothing, although we do need to take our chances when they come along.
“Overall I was pleased with the performance because we showed discipline and patience – everyone put in a really good shift.
“The boys are playing a lot of games at the moment and we have another under-23 match on Tuesday when the first team are at Coventry.
“It’s tough because we have a few injuries, but we welcome the challenge and just have to manage the schedule.”
Pompey: Ridley; Kavanagh (Bruce 21), Robb, Dandy, Kelly; Whiting, Read, Johnston; Bell, Stanley, Flint (Brook 58)
Sub not used: Rew