Nottinghamshire and Glamorgan, who faced each other in the YB40 final on Saturday, have been drawn in the same group for next season's 50-over tournament while there will also be Roses and London derby matches in the group stages.
The domestic one-day structure is reverting back to 50 overs from 2014 - to replicate the international format - and there will be two groups of nine with the top four from each qualifying for the quarter-finals.
Lancashire and Yorkshire have been drawn in the same group as have Middlesex and Surrey; teams will play eight group matches, four at home and four away. Netherlands, Scotland and Unicorns, who made up the 21 teams in the 40-over competition, will not be part of the new tournament, for which a sponsor has yet to be named.
Group A Leicestershire, Northamptonshire, Yorkshire, Worcestershire, Derbyshire, Essex, Gloucestershire, Lancashire, Hampshire
Group B Surrey, Somerset, Kent, Sussex, Glamorgan, Durham, Middlesex, Nottinghamshire, Warwickshire