Springboks coach Rassie Erasmus has reiterated that South Africa Rugby will rigorously enforce World Rugby Regulation 9 from 2020 in a bid to soften the impact of the growing flood of top players plying their trade abroad.
The regulation states that players must be released by their clubs for international duty for 14 weeks of the year, making them available for all South Africa's Tests in June, the Rugby Championship and November Internationals.
That would cut into a large part of the Northern Hemisphere club season, though, leave clubs without influential players unless the star names retire from international rugby.
South Africa Rugby has in the past taken a soft stance and allowed players to skip matches and tournaments so as not to put at risk their lucrative club contracts in France, England and Japan, where players can earn more in a two-month spell than by winning the Rugby World Cup with the Springboks this year.
With a raft of leading players already overseas, and more set to depart Super Rugby after the Rugby World Cup, Erasmus has warned clubs there will be no exceptions.
"Regulation 9 is there to make sure that all countries can compete and stay relevant on the world stage, and unfortunately with our exchange rate we are one of those countries now," Erasmus said at a press conference in Cape Town on Tuesday.
"Up until now we have had give-and-take because there are players' lives that are affected.
"But we are now saying that from 2020 we are going to enforce Regulation 9 because we can't pay people at that level [to compete with overseas contracts]."
"It is not about playing hardball.
"It is about being proactive and explaining to the clubs what we are doing.
"It gives the club who wants to sign a player the option to consider whether they want to go ahead. It gives the player the chance to decide whether he wants to go over there.
"Does he want to retire from international rugby and pick money now over playing for the Springboks? It is not a threat; it is a reality."
There are currently 36 South African players at Gallagher Premiership clubs in England, and 42 in France's Top 14.
Others, such as C.J. Stander and Quinn Roux (Ireland), and Willem Nel and Josh Strauss (Scotland), have gone on to play for the national teams of their adopted countries.
Sharks stars Robert du Preez and Akker van der Merwe recently signed contracts to play with Sale Sharks, their moves announced just days after South Africa Rugby had announced changes to its eligibility rules.