Pompey Academy brought a disappointing September to a close with a 3-2 defeat at Bristol Rovers.
The hosts went ahead against the run of play, only for Jordan Brooks (pictured) to level when he headed home from a Dan Smith free-kick.
There were more chances for the Blues before the break and Bradley Lethbridge fired narrowly wide before Matt Mayes had a shot saved.
But the Pirates made a bright start to the second half and restored their lead, then took advantage of their opponents pushing players forward to grab a third.
Mayes meet Lethbridge’s cross at the far post to reduce the deficit late on, but Pompey were unable to find a late leveller.
Lead professional development phase coach Mikey Harris said: “We were in control of the game during the first half, but didn’t take our chances when they presented themselves.
“It was a disappointing first goal to concede because they got through our midfield far too easily, although it was a good finish.
"We told the boys there would be a reaction from Rovers because we had been so dominant – and that’s exactly what happened."
“We’d had the lion’s share of the ball and the territory up until that point, but couldn’t make the most of that.
“Then we managed to get ourselves back on level terms, courtesy of a quality delivery from Dan and a show of desire and aggression from Jordan to get there first.
“At the break we told the boys there would be a reaction from Rovers because we had been so dominant – and that’s exactly what happened.
“Our decision making was simply not good enough in the second half and we just gifted them two goals.
“We fought to get back in the game and pulled one back following some good play, but the damage had already been done.
“It was a massive learning curve for the boys because we looked so comfortable and paid the price for making poor choices.”
Pompey: Collins; Kavanagh, Brooks, Casey (Mnoga 55), Hancott; Maloney (Flint 55), Read, Smith, Whiting (Stanley 66); Lethbridge, Mayes (c)
Subs not used: Birchnall