Pompey Reserves suffered a 1-0 defeat at Bristol Rovers in their first Central League Cup group stage match.
It was a youthful Blues side in action at Yate’s Lodge Road ground, with Alex Bass and Christian Oxlade-Chamberlain the only professional players featuring.
The only goal arrived midway through the first half when Cameron Ebbutt teed-up Kenan Dunwald to curl home.
Pompey were much better after the interval and their best chance fell to Bradley Lethbridge, who saw his shot cleared from the line.
Lead professional development phase coach Mikey Harris said: “The first half was disappointing from our point of view.
“We didn’t deal with the physical side of the game well enough, although our side was considerably younger.
"It was a great experience for our lads because playing a development squad is a step-up from under-18 football."
“There was a blatant handball in the build-up to the goal and it was frustrating that the referee didn’t spot that.
“But Bristol Rovers certainly had the better of the contest before the break and probably deserved to be ahead.
“We changed our shape slightly for the second half and were much more competitive, without creating many chances.
“I was pleased with the response and overall it was a great experience for our lads because playing a development squad is a step-up from under-18 football.
“It probably helped that we only had a couple of young professionals involved, as it meant the academy players had to work things out for themselves.”
Bristol Rovers: Andre Jr, Williams, Bailey (Kilgour 73), Ison, Kelly, Jones (Ten-Grotenhuis 88), Hargreaves, Russe, Ebbutt (Bhagdadi 73), Dunwald, Kavanagh
Subs not used: Armstrong, Leigh-Gilchrist
Pompey: Bass; Oxlade-Chamberlain, Casey, Dandy (Maloney 65), Hancott; Johnston (Whiting 46), Read, Brooks, Chandler; Mayes, Lethbridge
Subs not used: Collins, Flint