Cornwall coach Ian Morgan believes they "haven't really clicked yet" as they prepare to host Hertfordshire for a place in the County Championship final.
They must win at Redruth to top the Division 1 South table and reach Twickenham for the third year running.
Graham Dawe's side have already beaten Gloucestershire and Kent, but trail pool leaders Hertfordshire by a point.
"We know where our strengths lie, we haven't really clicked yet but that'll come," Morgan told BBC Radio Cornwall.
"We've got to make sure our discipline is good and we don't give any silly penalties away in crucial areas of the field."
|Bill Beaumont Cup Division 1 South|
Cornwall could play either Yorkshire, Cheshire or holders Lancashire in the final of the competition, also known as the Bill Beaumont Cup.
Max Venables is their only absentee for the crucial clash, after failing to recover from an injury suffered last week.
"If we give field position to Hertfordshire they're going to be as dangerous, if not more dangerous, than the other sides we've played," added Morgan.
"Defensively we have been good - our defensive shape has been excellent the whole tournament so far."
There will be live commentary from Redruth's Recreation Ground on BBC Radio Cornwall.
Cornwall team: B Searle, J Dawe, J Murphy (all Cornish All Blacks), N Webber, R Wedlake (both Redruth), L Webb (Taunton), M Shepherd (Cornish All Blacks); R Freestone (Clifton), J Salter (Cornish All Blacks), C Williams (Redruth), T Whittle (Camborne), B Hilton (Cornish All Blacks), C Fuca (Redruth), G Jones (Penryn), K Marriott (Redruth, capt).
Replacements: C Judge (Cornish All Blacks), T Phillips (Redruth), D Cook (Redruth), J Goldsworthy (Camborne), BJ Chapman (Cornish All Blacks), S Parsons (Redruth), D Mankee (Camborne).