Portsmouth suffered relegation heartache as two late tries condemned them to a 32-26 defeat against Dover at Rugby Camp.
The city club had safety in their sights as they led going into the final five minutes.
A disastrous finish, though, saw Dover score two tries – leaving Portsmouth in despair.
Coach Ian Chandler said: ‘Missing tackles and taking wrong options cost us.
‘We missed two straight one-on-one tackles.
‘We had done the hard work playing against the wind in the first half but then we failed to use the elements ourselves.
‘We were the only side in it during the opening 40 minutes and played the almost perfect game against the wind.
‘Every time we got in front we let them back into the game which was typical of us.
‘Our failure to kill teams off has been our Achilles’ heel all season.
‘I feel so disappointed for the players because of everything they put into it.’
Andy Barnes knocked over an early penalty, only for Dover to level with a dropped goal.
A superb Gareth Richards break, midway through the half, led to a Matt Gronow try giving Portsmouth an 8-3 lead.
And after the break, Portsmouth added a second try through Nick Lynch to put themselves in command of the contest.
Once again, though, poor play from the restart allowed Dover to nose 20-18 in front.
But Portmouth again established their superiority.
A Richards try, followed by a Barnes penalty, saw them leading 26-20 before they collapsed in the final minutes.
Portsmouth drop to London two south west, missing out on local derbies against relegated Havant and promoted Gosport & Fareham next season.
But Chandler remains upbeat and was given some encouragement after the game when the players voiced their intent to bounce back
‘As a club we are disappointed but not disillusioned,’ said Chandler.
‘The players had a meeting afterwards and decided that no-one was going to leave.
‘They have vowed to stay put and help get us back up next season.
‘The players have accepted the responsibility and are determined to remain positive.’