Pompey Academy’s final fixture of 2016 ended in a 2-0 defeat to Oxford at Furze Lane.
Matt Mayes and Sam Woodward both had chances to open the scoring as the hosts looked to forge ahead in the early stages.
But they found themselves behind midway through the first half and then struggled to carve out clear-cut openings.
The Blues were forced to make a change after the interval when Matt Casey got injured and it soon got even worse as Oxford doubled their advantage.
United had to play the final moments with just 10 men following a red card for a second bookable offence, but there was not enough time for Pompey to make their numerical advantage count.
Academy coach Mikey Harris said: “We’re obviously frustrated by the result, although I can have no complaints about our application and work-rate.
“The boys tried hard, but the quality was lacking at times and I know we can perform much better than we did.
“It was a difficult game to be involved in and soon became a very scrappy affair, while a number of decisions didn’t go our way.
“That had a negative effect on the players and it’s a lesson they must learn – you can only focus on things you can control.
“We created a number of chances to get back into the game, but we’re disappointed with the goals we conceded.”
Pompey: Collins; Smith, Casey (Wakley 50), Saidy, Hancott; Widdrington (c); Bedford, Scutt; Woodward; Bradbury, Mayes
Subs not used: Hall, McDowell