Pompey struck two second half goals to secure an impressive victory at previously unbeaten Plymouth in Merit League One.
One of the visitors’ trialists bagged a brace in Devon, with both goals being assisted by Harvey Hughes.
Toby Steward had earlier denied Freddie Issaka, while the keeper then ensured a clean sheet by saving a shot from Jamal Salawu.
The result saw the Pilgrims knocked off the summit, while boosting the Blues’ hopes of a top-three finish.
Professional development phase coach Liam Daish said: “I was really pleased with both the result and the performance.
“Plymouth are always tough opposition, but we defended well and then took our chances when they came along.
"t was a very competitive contest and our lads passed the physical test, having to show a different side of their game."
“Our trialist finished nicely on both occasions and I thought that Harvey was our best player, maintaining his high standards.
“It was a very competitive contest and our lads passed the physical test, having to show a different side of their game.
“They adapted to that well and remained responsible at the back, while keeping their concentration levels throughout.
“It was also pleasing to see Liam Vincent get 90 minutes under his belt for the first time in a long while.
“Hopefully that will give him some confidence to take into the summer as he looks ahead to next season.”
Pompey: Steward; Aston, Vincent, Hughes, Laidlaw (Trialist 78); Jewitt-White, Bosaka (Trialist 46); Kamavuako, Trialist, Howell; Trialist (Hurst 78)