Portsmouth’s three-game winning run in London two south west came to an end with a 27-25 defeat by KCS Old Boys at Rugby Camp.
The hosts led 25-20 with two minutes remaining but conceded a crucial penalty inside their own half.
After the visitors kicked to the corner, they won the line out and drove over for a try before landing the conversion to snatch the spoils.
Assistant coach Jim Pearce was disappointed because he felt it was a chance lost.
He said: ‘After getting into the position we did, it was frustrating not to hold on.
‘We started slowly and it took us a while to get control.
‘Once we did KCS couldn’t live with us.
‘They were a young side who played with a quick tempo, so we adjusted to deal with that.
‘We got our forwards to run hard and fast at them to slow the game down to a pace we could work with.’
Portsmouth quickly found themselves 14-6 down after a slow start.
Simon Morgan knocked over two penalties but it wasn’t until the 48th minute that the hosts scored their first try.
Luke Richardson made the break and when the ball was recycled Anthony Fooks went over in the corner.
After conceding another penalty, Portsmouth scored an excellent try from a counter-attack.
Hamish Laybourne provided a good delayed lofted pass and Fooks went in for his second.
The hosts got their noses in front when Tom Whitehouse gathered the ball after a tackle to score – with Morgan again converting.
‘Hopefully we can learn from this,’ said Pearce.
Southsea Nomads showed plenty of spirit despite suffering a 70-8 mauling at the hands of Hampshire two leaders Overton at Furze Lane.
Peter Pridmore, the oldest man on the pitch, had a stellar game at scrum-half after a last-minute call-up.
In the second half, Nomads shocked Overton by scoring a try, the first the visitors had conceded in 400 minutes.
Joby Walsh was awarded man of the match after a typical performance, claiming restarts and producing strong runs throughout the game.
‘Despite the scoreline, this is the best I have seen Nomads play for a long time,’ said stand-in captain Aaron Beesley.