Pompey Academy battled from behind to beat Bournemouth 3-1 at Copnor Road in the Merit League.
The visitors – who had the grandsons of former Blues bosses Alan Ball and Harry Redknapp in their side – took the lead through Jonny Stuttle.
But Harry Clout then sent in a cross for Maxwell Hurst to volley home and ensure the teams went in level at the break.
Sam Folarin’s powerful finish saw Pompey go ahead early in the second half and the same player wrapped up the points moments later.
Lead professional development phase coach Sam Hudson said: “It was a very good win and a positive performance against the side who won the Youth Alliance League title a few weeks ago.
“We played a diamond for the first time this season and with various players going out on loan and trying to blood some younger ones, we didn’t really have a traditional training week to prep that.
“But they took to it well and pressed really aggressively, nullifying their build-up – which is probably the strongest part of Bournemouth’s game.
“An individual error saw us fall behind, but we rallied and fought back to deservedly come away with all three points.
"While we are very happy with the result in the short-term, the game also showed that we’re looking healthy in the long-term."
“All three goals came from our centre-forwards and that’s something we’ve been working with them on, so that was pleasing.
“It was a nice first-time finish from Maxwell and Sam’s came from mazy dribbles – I think he beat four players for one of them.
“There were more chances, some of which came from our press and some as a result of good play out from the back.
“Harry from our under-16s started his first game at this level and in the first half especially, was absolutely fantastic, making lots of dangerous forward runs.
“Christian Ayres at right-back is only 15 and playing a couple of years up. He got through 90 minutes and was strong in his duels, making very few mistakes.
“Jayden Keteku also got time on the pitch in the second half and did a good job as an attacking midfielder.
“So while we are very happy with the result in the short-term, the game also showed that we’re looking healthy in the long-term in regards to players coming through."
Pompey: Osei-Owusu; Ayres, Bosaka, Fox, Laidlaw; Aston; Payce, Murray (Keteku 68); Clout; Hurst (Ojo 72), Folarin