Pompey Reserves collected their first Premier League Cup point of the season after drawing 2-2 with Exeter in Bognor.
But the youthful Blues side will be disappointed not to collect all three, having twice led through goals from Bradley Lethbridge and Matt Casey.
The first half was a cagey affair, although Harvey Rew nodded narrowly over the crossbar for the hosts.
Pompey started strongly after the break and opened the scoring when Lethbridge collected Rew’s fine pass and neatly slotted home.
Stan Bridgman came close to doubling their advantage moments later, only to see his long-range attempt fly narrowly over.
But the Grecians found themselves level just past the hour mark, as Theo Simpson curled a shot into the top corner.
The Blues almost immediately restored their advantage, however, with Casey rising highest in the box to head home from a Leon Maloney corner.
"Every single one of them put in a real shift and also displayed some real quality."
Taylor Seymour had looked composed between the sticks and kept the hosts ahead with a couple of smart saves.
But Exeter snatched a draw late on, as Ben Seymour slipped a shot under his namesake to cap a neat move.
Academy manager Mark Kelly said: “We showed a really good attitude. All the lads had a willingness to compete and work hard – on and off the ball.
“We unfortunately couldn’t hold on against a more experienced side, but every single one of them put in a real shift and also displayed some real quality.”
Pompey: Seymour; Kavanagh, Casey (c), Rew, Kelly (Robb 65); Storey, Bridgman; Maloney, Flint, Lethbridge (Teggart 56); Stanley (Brook 83)
Subs not used: Bruce, Bell