World Rally Championship manufacturer teams will only have to nominate a driver for 10 rounds instead of the whole season in 2014.
Previously, manufacturers have been obliged to name one driver who will contest all 13 rounds of the series.
But this move - which was pushed hard by the Citroen team - comes courtesy of a lack of frontline drivers in the sport.
The FIA World Motor Sport Council decision stated: "In order to allow greater flexibility to contract different drivers, manufacturers will no longer be required to nominate one permanent driver for the season.
"Instead, manufacturers will be obliged to nominate one driver for a minimum of 10 championship events."
One leading team manager said he could see the reason for the change in regulation but feared it could return the WRC to running specialists for certain events.
"Remember when Peugeot brought [Giles] Panizzi in for asphalt rallies," he said, "or Harri Rovanpera on the snow in Sweden?
"It gave the richer teams the chance to buy more drivers and score more points.
"Let's hope this doesn't happen this time around."
Newcomer Hyundai has nominated lead signing Thierry Neuville for the full 2014 season but has already signed Juho Hanninen and Dani Sordo for what will only be partial programmes in its second car.