Liam Daish was delighted with the performance of his young charges at AFC Stoneham in the Hampshire Cup.
A Pompey side full of academy players saw off Wessex League opponents to progress to the quarter-finals.
Alfie Bridgman’s goal was cancelled out by Duarte Martins to send the third round contest to penalties.
But the Blues won the shoot-out 5-4, with substitute Jamie Howell calmly converting the decisive spot-kick.
Professional development phase coach Daish said: “The lads played really well, although we probably didn’t keep the ball well enough in the second half.
“That meant Stoneham still had an interest in the game and it was sod’s law that they equalised so late in the game.
"They’ll learn a lot about how to manage games and it’s all about those learning experiences at this stage of their careers."
“But we held our nerve to win on penalties and get through to the next round, which was a great experience for them.
“They were disappointed when they came off at the final whistle, so we had to remind them that it wasn’t over. There were some excellent penalties from them.
“They’ll learn a lot about how to manage games and it’s all about those learning experiences at this stage of their careers.
“I’ve seen a lot of development from this group of players since pre-season, with some guys having been out on loan or around the first team environment. They’ve grown as people and as players.
“There were some really good performances out there, with Alfie starting the game in a really positive manner.
“Dan Gifford and Harry Jewitt-White were a real threat for us and a lot of the others did well as well.”