Pompey conceded two late goals to slip to defeat against Fulham at the Wellington Sports Ground.
The Blues took the lead after just four minutes when Carl Walshe (pictured) fired home from the penalty spot.
But Karim Frei quickly equalised for the Cottagers and then added a second on 20 minutes.
Pompey hit back after the break and Lewis Tallack drew them level before Alex Grant’s goal gave the hosts the lead.
However, with just 10 minutes remaining Stephen Arthurworry scored for Fulham and Marcella Trotta struck at the death to give the Londoners all three points.
Director of youth operations Paul Smalley said: “We produced our best all-round performance of the season and although we were trailing at half-time we had shown plenty of endeavour and energy.
“Midway through the second half we had overturned our deficit to lead 3-2 but some poor defending from a corner and a late strike meant it was a cruel end to an otherwise pleasing day.
“Carl Walshe again produced a fine performance and most of the side performed well against an excellent Fulham side.
“All of the first-year scholars are starting to adjust to their responsibilities in their football education. They are getting stronger and fitter, starting to understand the game better and certainly enhancing their skills.
“The group has a good work ethic and togetherness and there is a nice atmosphere. But it will still take time to turn their performances into better results.
“We are still at a very early stage of the season so it is important that the players reflect, learn and understand from game to game, to make the necessary progress.
“We are bottom of the table but most of our defeats have been by just a one or two-goal margin and the players’ learning and understanding is developing and certainly moving in the right direction.
“So we will be looking forward with excitement to our next game and certainly demanding the same level of performance.”
Pompey: Gledhill; Tallack, Bennett, Magri, Grant; Seeley (Fitzharris 75), Stockford (c), Tsovolos (Harris 67), Butler; Jennings (Colson 71), Walshe
Fulham: Bettinelli; Monguel, Arthurworry, Maloney, Kamau; Barroihet (Cosgrove 84), Pritchard (Banya 35 (Owusu-Awah 65)), Minkwitz, Harris; Trotta, Frei
Sub not used: Miller-Rodney
There was a better result for Pompey’s under-16 side who drew 1-1 with Fulham.
Smalley said: “They took the past month of good displays to the next stage with a consistent performance of energy, hard work and desire.”