Pompey Academy lost an 11-goal thriller at Cheltenham – despite leading with just a few minutes remaining.
The hosts took an early lead from the penalty spot, only for Jez Bedford (pictured) to nod home a leveller after a throw had been flicked on by Eddie Wakley.
Harvey Bradbury and Jordan Brooks then both went close to giving the Blues the lead, but it was Cheltenham who were next to score again.
Pompey continued pushing forward, however, and equalised for a second time when Tommy Scutt’s free-kick was kept out and Bradbury was quickest to the loose ball.
And they took the lead from the penalty spot just before the break, with Scutt finding the target after Sam Woodward had been brought down in the box.
Cheltenham ensured it was all square again early in the second half, but Bradbury headed home a Dan Smith cross to restore the Blues’ advantage.
The sides continued to swap goals, with the Robins drawing level and Smith then finding the target for the visitors.
It looked like that had ensured the points would be going back down to the south coast, but Cheltenham equalised before grabbing a last-gasp winner on the break.
Academy coach Mikey Harris said: “If you score five goals away from home then you expect to come away with the victory.
“I went away not quite being able to believe what I had just seen, especially because we were leading so late in the game.
“We played very well with the ball and created a number of chances – around four times the amount that Cheltenham managed.
“Possession was dominated by us and – although it sounds crazy – we probably should have netted more than five goals.
“But we were nowhere near good enough defensively and didn’t get tight enough to their crosses or shots.
“It’s obviously pleasing to score so many, but the lads have to learn that – however dominant you are – if you can’t keep the ball out at the other end, then you won’t win football matches.
“We were the better side in the middle of the pitch, but games are won in both boxes and that’s clearly something we have to work on."
Pompey: Collins; Smith, Saidy (Casey 61), Wakley, Hancott; Brooks (Lethbridge 70); Scutt, Bedford; Woodward; Bradbury, Mayes (Chandler 65)
Subs not used: Hall, Read