Portsmouth had their London three south west promotion hopes dented following an 18-10 defeat at Warlingham.
The Norway Road outfit slipped to third in the table and lost ground on leaders Winchester.
Neil McRoberts rated Portsmouth’s performance as their worst of the season.
However, he knows the Hilsea club’s promotion fate still rests in their own hands.
The senior coach said: ‘It was exceptionally disappointing. I would rate it as probably our worst of the season.
‘We just didn't turn up and failed to start playing until the 70th minute.
‘By then it was far too late to achieve anything.
‘We have said what needed to be said and I am sure the players will react in the right way.
‘Our fate is still in our own hands because we still have to play all the teams around us.
‘What it does mean is that we can't afford any more slip ups.’
Meanwhile, United Services gained ground on their city rivals with a thumping 43-5 win at Teddington.
Player-coach Rich Neil was relieved to see his team get back to winning ways.
‘Since Christmas we have been inconsistent in our execution,’ he said.
‘We worked harder, were more accurate and got our rewards.
‘Our next two games against Warlingham and Portsmouth are big ones for us.’
Petersfield suffered a 43-12 defeat against Battersea Ironsides at Penns Place.
In Hampshire two, Southsea Nomads returned to the winning trail with a 39-12 home success against Basingstoke II.
Nomads had to work hard early on to subdue a heavier Basingstoke pack.
After conceding the first try, Nomads hit back powerfully to open up a 22-7 lead at half-time.
Gregory Stewart, John Marsden and Jonathan Branston all claimed tries.
Branston also added a penalty and three conversions.
Further home tries followed in the second period courtesy of Branston, Josh Soper and Ben Horrod.
‘It is great to get back to winning ways,' said captain Horrod.
‘The lads put in a strong performance – particularly the forwards.
‘There are still things to work on, however.’
Joe O'Connor-Simpson made his debut and Soper picked up the man-of-the-match award for his fine defence, work-rate and excellent support running.
Nomads remain in fourth spot and five points adrift of third-placed Chineham.