FIFA has imposed conditions on the release of players for the South American World Cup qualifiers amid concerns over high coronavirus infection rates, travel difficulties and quarantine rules.
FIFA said on Thursday the usual rules over the release of players for the games -- which are due to get under way next week -- would apply but with exceptions.
Football's world ruling body said players must be exempted from any travel or quarantine restrictions, both in the countries where they are due to play matches and in the country where their clubs are based.
If there was a quarantine period of five days or more on arrival in any of those countries, then clubs would not be obliged to release them.
The South American football confederation (CONMEBOL) announced last month that the competition would start in October and that it had FIFA's approval.
Many of the world's top players from leading European clubs are involved in the games, including Barcelona's Lionel Messi and Paris Saint-Germain's Neymar, who play for Argentina and Brazil respectively.
"FIFA together with the confederations and member associations will continue to monitor the situation regarding the travel and quarantine policies of the relevant authorities in relation to the upcoming international matches," FIFA said.
The global players' union FIFPRO said last week it had multiple concerns about the games and that players should not be forced to travel if they did not feel safe.
The South American competition will start on Oct. 8 with three matches -- Paraguay vs. Peru, Uruguay vs. Chile and Argentina vs. Ecuador, with Colombia vs. Venezuela and Brazil vs. Bolivia one day later. There is another round of matches on Oct. 13.
European countries have collaborated so the UEFA competition matches can be played. However, it was not immediately clear whether European countries would grant exemptions to players returning from matches in South America.
Nearly all the leading South American players are based abroad, mainly in Europe. But there is also a large contingent of players in Major League Soccer, including nine in Peru's 30-man preliminary roster. Paraguay has six MLS players on its initial roster, including New York Red Bulls midfielder Kaku.
Other players that could be impacted are the Uruguay duo of Diego Rossi and Brian Rodriguez, both of LAFC, as well as LA Galaxy attacker and Argentina international Cristian Pavon.
MLS president and deputy commissioner Mark Abbott told ESPN's Jeff Carlisle that it will be the individual club's decision to release any player for international duty. The qualifiers come as teams are entering the tail end of the season ahead of the MLS playoffs in November.
"I think that this isn't your typical club and country dispute, where clubs are reluctant to lose players during the course of season and things like that. I think people have very legitimate health and safety concerns that they're trying to consider. And I think there's just gonna have to be ongoing dialogue throughout the soccer community," said Abbott.
MLS currently requires players arriving from abroad to quarantine for minimum of 10 days. Canada, in which three MLS teams reside, has a 14-day quarantine period.
"We can understand why a club would have a concern about a player going on international travel in matches that that would have perhaps different testing cadences than what we have. And this isn't to criticize the protocols, I think that people are trying to implement.
"It's just a challenge to have protocols that can mitigate the risks inherent in international travel. And I think those are sort of the health and safety considerations that clubs rightly should be able to consider in determining whether to release players or not," said Abbott.
Both Asia and CONCACAF -- the North and Central American and Caribbean regions -- have postponed qualifiers until March due to COVID. However, top-ranked CONCACAF side Mexico will play two friendlies in the Netherlands, against their Dutch hosts on Oct. 7 and against Algeria on Oct. 13.
Several MLS and Liga MX-based players have been called up by Mexico manager Gerardo "Tata" Martino, which has caused concern among some of the club bosses.
Galaxy coach Guillermo Barros Schelotto, who may also lose Jonathan dos Santos for those Mexico games, inferred that the club would prefer to keep him.
"For now, the player has to go with the Mexican national team next week, but if FIFA gives us the possibility of the teams deciding and keeping the player, because of COVID and the quarantine, we will [decide]."
Inter Miami CF boss Diego Alonso was more direct about the possibility of losing Rodolfo Pizarro for Mexico duty.
"If we have the obligation to release Rodolfo, we'll do it, and if we aren't obligated to, he'll stay with us," said Alonso.
ESPN's Jeff Carlisle and Tom Marshall contributed to this report. Information from Reuters was also used.