Pompey Academy twice battled from behind before eventually slipping to a 3-2 defeat at Cheltenham in the Youth Alliance League.
They recovered from going behind after just five minutes when Connor May (pictured) headed home Brian Quarm’s cross.
The Robins restored their lead from the penalty spot and although Maxwell Hurst converted a Koby Mottoh delivery to equalise, the hosts grabbed a late winner.
Lead professional development phase coach Sam Hudson said: “We had a really slow start and conceded an early goal – we just didn’t get going and were sloppy in all areas.
“But then there was an injury break that happened at a good time. It allowed us just to settle down a bit and look to start again.
“We were excellent for the rest of the first half and got ourselves back on level terms with a well-worked goal.
“It was then an onslaught from us – we hit the bar, we hit the post and there were shots cleared from the line.
"Given the earlier period of dominance, it was incredibly frustrating and we know that we can do a lot better than that."
“We created enough chances in the space of around 30 minutes alone to win the game, but just couldn’t find that second goal.
“It was incredibly dominant and so we told the lads at half-time to just continue what they had been doing.
“But then we produced a poor performance after the break. Our decision making wasn’t great and we were trying to make passes that just weren’t on. We made life hard for ourselves.
“We just needed to make short and simple balls to overload our opponents in the wide areas – when we did that we found success and looked a good team.
“But we went behind again after giving away a poor penalty and there were defensive errors throughout that cost us.
“We got level again through Max, but then conceded a third late on. It was a great strike into the top corner, but there were mistakes in the build-up to that.
“Given the earlier period of dominance, it was incredibly frustrating and we know that we can do a lot better than that.”
Pompey: Glover; Quarm, Bosaka, Howard, Mullins; Murray, Staight; Mottoh, Clout, Folarin (Hurst 73); May