Portsmouth left it late before picking up a first London two south west win of the season.
The Rugby Camp outfit claimed a 21-18 success over Effingham & Leatherhead on home turf.
Portsmouth were staring a fourth straight defeat in the face when the visitors took a 18-14 lead with just 60 seconds left of the match.
However, the home side displayed a great never-say-die attitude to hit straight back with a converted try of their own before the full-time whistle.
Damian Gibbs forced his way over for his second try of the game with Simon Morgan adding the conversion.
Portsmouth’s assistant coach, Jim Pearce, admitted the closing stages were no good for his nerves.
‘It is such a relief to get the first win under our belts,’ he said.
‘When they scored towards the end we were all left shaking our heads.
‘However, some of the more experienced players got the team together and gave them a talking to.
‘From the restart we put together 18 continuos phases before going over for our try.
‘The forwards showed great composure in making sure there were no mistakes.
‘They had a desire not to lose the game.
‘You could see when the final whistle went what it meant to them.’
The visitors scored the only try of the first half.
However, the home side took a 9-5 advantage into the break courtesy of three Andy Barnes penalties.
Two further kicks at the start of the second half put the visitors ahead.
Gibbs, who had gone on as a replacement at half-time, restored Portsmouth’s lead with the first of his tries on the hour mark.
The number eight picked up at the base of a five-metre scrum and powered his way over the line.
It looked bleak for Portsmouth when they were outflanked a minute before the final whistle time to concede a converted try.
But in a remarkable finale Gibbs snatched the winning score.
‘It was great to see some of the things we have been working on in training coming to fruition on the pitch,’ added Pearce.
Elsewhere, United Services suffered a 31-19 defeat at Teddington in London three south west.
And in Hampshire League division two, Southsea Nomads were granted a walkover after visitors Lymington Mariners failed to raise a team.