Steve Evans admitted Peterborough could have no complaints with final-day defeat.
But he believes his side will return to Fratton Park next season and cause Pompey more problems.
Evans admitted his team were second best as they fell to a 2-0 defeat on the last outing of the season.
The Posh boss knew they couldn’t afford Brett Pitman the space to get the two goals which made the difference.
Evans felt the second of those goals was offside, but wasn’t prepared to offer that up as a reason for why his team come up short.
The Scot feels Pompey will be a threat under Kenny Jackett next term – but so will his players as he sets about making a mark with the club he joined in February.
Evans said: ‘You can’t give a striker with the class of Pitman a free header from three yards. The second one we felt was offside, but the angle was tight.
‘We had to change at half-time to get some presence up the pitch. We had a couple of half opportunities, but Portsmouth deserved to win the game. No complaints.
‘We’ll be back next season and be much stronger, but under Kenny they’ll be stronger, too.’
Peterborough left out League One’s top scorer Jack Marriott with speculation rife of a move for the striker being on the cards.
Evans acknowledged that is likely to happen – and changes are on the cards at London Road‑.
He added: ‘There was never a question of Jack coming on.
‘The football club is in dialogue with some good football clubs who want to take Jack Marriott.
‘If it happens we wish him every success.
‘The football club’s in talks for a reason.
‘The chairman showed loyalty to the management in January to keep him to see if we could force it over the line, but sadly too many links in the chain are badly amiss.
‘I have to be ruthless in the process – I’ve not come here to watch that.’