Gosport & Fareham shocked Guildford by inflicting a surprise 18-12 defeat on the London south-west two promotion-chasing visitors at Gosport Park.
Guildford rocked their hosts with a second-minute try and spent the opening 15 minutes camped on the home line.
Jamie Daly’s side, however, kept them out and hit back to lead by half-time.
Sam Foster knocked over an 11th-minute drop goal before Alex Duncombe took charge, adding a penalty and converting his own try.
Guildford came back with another try on the hour mark but Gosport & Fareham finished the stronger, with Wes Dugan going over for a try eight minutes from time.
‘I think that was the best performance by the team this season, and to win is absolutely fantastic,’ said director of rugby Daly.
‘We went out there with the attitude that we were going to do everything we could to win that game and I would expect nothing else from us as a club because that is what we are all about.
‘Guildford were all-guns blazing right from the beginning and were camped on our line for a good 15 minutes when they turned down the chance of points from penalties because they needed a bonus-point win.
‘We did concede but we came back at them and there was a focus right through our team to win and show that we are not deserving of the nine-place position we are in the league.
‘We are where we are for our performances through the season as a whole but we are not where we could’ve been.’
In Hampshire One, Fareham Heathens were crushed 59-0 by Eastleigh at Cams Alders and United Services Portsmouth suffered a 46-10 reverse at Southampton.
Hampshire Two champions Southsea Nomads finished on a winning note after they beat Fawley 45-22 on the Waterside.
Andy Marsh (2), James Hardy (2), Dan Tyler, Damian Parker and Dan Mitchell all crossed for tries, with Chris Smith adding five conversions.