An unusual scenario has transpired whereby a number of Premier League clubs find themselves at odds with the Brazil football association (CBF) and other South American associations.
Liverpool, Manchester United, Manchester City and Chelsea are among the high-profile teams that will potentially be affected, with the national associations invoking a FIFA rule to prevent players from playing.
So what exactly is the rule, which players are at risk of missing out and why has the entire saga developed in this way? Goal has all the details.
What is the five-day FIFA rule affecting players in the Premier League?
The rule in question here is Annexe 1, Article 5 of FIFA's Regulations on the Status and Transfer of Players.
Designed to protect national teams from unnecessary club-influenced withdrawals, it effectively prevents players who have been called up for international teams from playing for their clubs during the time they should have been released for duty - plus five days after the international window.
In this particular instance, that additional five days covers the period September 10 to September 14.
The wording of Article 5 reads: "A player who has been called up by his association for one of its representative teams is, unless otherwise agreed by the relevant association, not entitled to play for the club with which he is registered during the period for which he has been released or should have been released pursuant to the provisions of this annexe, plus an additional period of five days."
How did the dispute arise?
It is a classic 'Club versus Country' dispute.
Ahead of the September 2021 international window, Premier League clubs "reluctantly but unanimously" decided not to release players to the United Kingdom's 'red list' countries due to the need for them to quarantine for a period of 10 days upon their return.
A statement from the league explained: "If required to quarantine on return from red list countries, not only would players’ welfare and fitness be significantly impacted, but they would also be unavailable to prepare for and play in two Premier League match rounds, a UEFA club competition matchday and the third round of the EFL Cup."
As well as the Brazil football association, the governing bodies for the Mexico, Paraguay and Chile teams have also invoked the rule, in protest at the refusal to release players.
Diplomatic efforts have been made involving representatives from the Premier League clubs, FIFA and the national associations in an attempt to amicably resolve the situation.
Which Premier League players are affected?
A number of key players from Manchester United, Liverpool, Manchester City and Chelsea are affected, along with players at Wolves, Newcastle United, Leeds United and Watford.
Liverpool duo Alisson and Fabinho will be affected should the rule continue to apply (Roberto Firmino is out with injury), while Ederson and Gabriel Jesus will be precluded from playing for Manchester City, though Jurgen Klopp and Pep Guardiola are both hopeful they will be involved.
Others from the Brazilian cohort include Chelsea defender Thiago Silva is set to be affected, as will Manchester United midfielder Fred and Leeds United forward Raphinha.
Wolves and Mexico striker Raul Jimenez was set to be affected too, though the Mexico association withdrew their complaint. Others to be affected are Watford's Chile international Francisco Sierralta and Newcastle's Paraguay midfielder Miguel Almiron.