Pompey Reserves cannot reach the knockout stages of the Premier League following a 4-2 defeat to Doncaster.
Paul Downing skippered a youthful side, with Adam May and Matt Casey the only senior players to feature.
And the visitors stormed into a convincing interval lead, with goals from Danny Amos, Rian McLean and Myron Gibbons.
They increased their advantage through a trialist after the break, but the Blues at least mounted a late fightback.
Haji Mnoga nodded home a right-sided free-kick, while Leon Maloney then finished neatly at the far post.
Pompey still have two group fixtures remaining – against Exeter and Aston Villa – but cannot finish in the top two.
Pompey: Seymour; Mnoga, Downing (c), Casey, Rew; May, Storey, Bridgman (Bell 60); Maloney, Stanley (Teggart 68), Lethbridge
Subs not used: Bruce, Robb, Kelly