Only Under-21 players will now take part in the SAB Regional League.
Unlike in the past when teams were allowed to select six players over 21, the South African Football Association is pushing for a more developmental approach.
Safa's competitions director Balebetse Monnakgotla the new rule will apply for the first time in the playoffs scheduled for Free State next month.
The inaugural SAB under-21 national championships will be played at various venues in Bloemfontein from April 13 to 18.
"It's no longer winning clubs going through to the national playoffs as it was done in the past - we have selected provincial teams," Monnakgotla said.
He says teams will be forced to field five under 21 players in the Regional League.
"The idea of insisting on five young players being part of every game is to encourage development.
"It's no longer going to be a league of legends."
Monnakgotla said Amajita coach Serame Letsoaka will also be in Bloemfontein to select a training team that will be integrated into the team.
"For the very first time, we will also have a team from University Sport Association of SA."