Devon chief executive Neil Gamble has said he expects "an edge" to their Unicorns Trophy clash with Cornwall.
They have named an unchanged 12 for the game at Sidmouth in the one-day cup.
"There's an intimacy about it but there's also a rivalry," Gamble told BBC Sport.
"There's a little bit of an edge obviously because some of the players have played both in the Devon league and in the Cornwall league over the years."
Holders Devon are one win away from qualifying for the knock-out stages, having beaten Dorset and Bournemouth by four wickets so far.
Cornwall skipper Matt Robins has recovered from a finger injury and replaces Tom Rowe, while Justin Stephens could make his first county appearance since 2010.
Devon: R J Woodman (Taunton Deane), L J Lewis (Sidmouth), M C Golding (Bovey Tracey), M W Thompson (Torquay), S J R Wyatt-Haines (Clevedon), A P W Allen (Exmouth), T W Allin (North Devon), C L Miles (Sidmouth), T S Anning (Exmouth), B G F Green, Z C G Bess (both Exeter), M C Curtis (North Devon).
Cornwall: M L Robins (Grampound Road), M H Rowe (Henley-on-Thames), S A Harvey (Truro), B L Wadlan (Bridgend), C B F Purchase (Falmouth),, M J Bone (St Austell), P S Smith (Werrington), A J Cocking (Newquay), K J Snell (Truro), C J Wilson (St Austell), G E Furnival (Falmouth), J C J Stephens (St Just).