Pompey Academy’s Youth Alliance League title hopes received a blow as they were beaten 5-3 at rivals Plymouth.
It means they have to win both of their remaining games – away to Bournemouth and Oxford – to have any chance of sealing top spot.
The Pilgrims roared into an early lead through a Will Jenkins-Davies free-kick and a Freddie Issaka penalty.
But the Blues hit back and Adam Payce reduced the deficit before Gabriel Kamavuako was fouled in the box and scored the resulting spot-kick.
The visitors were then awarded another penalty following a handball short after the interval and this time Jamie Howell (pictured) stepped up to convert it.
Argyle finished the contest strongly, however, and goals from Oscar Halls and Oscar Massey turned the contest in their favour.
Angel Waruih then wrapped things up right at the death with an incredible strike from the halfway line.
Professional development phase coach Liam Daish said: “It would have been a good game for the neutral, but we conceded two sloppy goals in the opening stages.
“We gave away possession far too cheaply and then committed a couple of fouls that led to goals, so that was disappointing.
“But we got back into the game through Adam following some good work from Gabriel down the left.
"We have to show what we’re made of because I thought we buckled at times."
“Gabriel then got himself in the box and forced the defender to make a rash decision before getting up to dispatch the penalty.
“We got our noses in front early in the second half from another spot-kick, which this time was taken by Jamie.
“From there we probably thought we’d done enough, but Plymouth were an older side and you could see how competitive they are.
“They asked a few questions of us and we didn’t answer them properly, not defending set-pieces the way we should be.
“It was a tough end to the game from us and they got a couple more – one was decent, but the other we could have done better with.
“We needed to be more resilient in those times when our backs are against the wall. We have to show what we’re made of because I thought we buckled at times.”
There was reason to celebrate for Toby Steward despite the scoreline, with the keeper signing his first professional contract earlier in the day.
Daish said: “It's a really great achievement for him and something that he should rightly be very proud of.
“You sign the first contract on potential – and we know he’s got heaps of that – but the next ones will be more about performance and are even more difficult to earn.
“Toby’s got a lot of hard work ahead of him, but knowing him as I do, there’s a real desire to keep getting better.”
Pompey: Steward; J.Fox, Spurway (Aston 61), Kaba, Bridgman; Simpson (Hurst 76), Bosaka, Dockerill; Kamavuako, Payce (Laidlaw 76), Howell