Pompey Academy built on their FA Youth Cup success earlier in the week with a 2-1 league victory over Plymouth at Furze Lane.
They took an early lead when Oscar Johnston fired home after an initial effort from Matt Mayes had been blocked.
But Argyle levelled just seconds later and although Mayes and Josh Flint both went close to restoring the advantage, it was all square at the break.
Victory was secured for the Blues midway through the second half, however, thanks to a superb team goal.
Bradley Lethbridge worked the ball out wide to Flint and his cross was converted by a diving header form substitute James Whiting.
Lead professional development phase coach Mikey Harris said: “I’m really pleased with the overall performance and we’re improving all the time.
“We were much better than at Gillingham on Tuesday evening and there were some excellent individual displays.
"We were a real threat on the counter-attack, while showing plenty of resilience and character to secure the win."
“It gives us a selection headache ahead of the FA Youth Cup match against Lewes at Fratton Park on Friday. Everyone involved has put up a good argument for playing.
“We had to withstand a barrage of pressure in the second half, with Plymouth sending a lot of set-pieces into our box, but we held firm.
“And we were a real threat on the counter-attack, while showing plenty of resilience and character to secure the win.
“Our focus now turns to Lewes and we hope that plenty of Pompey fans will come out to show their support.”
Pompey: Collins; Chandler (Whiting 66), Dandy, Casey, Hancott; Johnston, Brooks, Read (Smith 46), Flint; Maloney, Mayes (c) (Lethbridge 46)
Sub not used: Birchnall