Teams competing in next year's FIFA Club World Cup must arrive in the United States three to five days before their first game, FIFA confirmed via tournament rules published on Tuesday.

This leaves players facing the prospect of no rest days between international World Cup qualifiers and the start of the club tournament.

FIFA has contacted qualified teams for the 2025 Club World Cup -- a 32-team, 63-game tournament which starts on June 15 -- with their rules and regulations for the tournament which will conclude with a final at a yet-to-be-announced venue on July 13.

As part of the newly disseminated rules, clubs were also told they must field their strongest teams in games and face fines if they fail to do so, the source told ESPN.

The tournament, a project driven by FIFA president Gianni Infantino, has led to growing unrest within the game as players' unions and league associations taking action against FIFA in the European courts.

Leading players have also voiced their concern over the amount of games they are being forced to play with coaches including Manchester City's Pep Guardiola and Real Madrid's Carlo Ancelotti complaining about the workload on their squads.

And with an international break scheduled between June 6-10 next year for qualifying games for the 2026 World Cup, FIFA's insistence on clubs arriving in the U.S. three to five days before their first game could see international players forced to represent their national team less than a week before playing in the Club World Cup.

The Champions League final is due to be staged in Munich on May 31 -- a week before the international break -- and it raises the prospect of players from City, Real Madrid and Bayern Munich going from a Champions League final, into and international round of fixtures, and then the Club World Cup without the prospect of a break until mid-July.

FIFA's Club World Cup regulations also state that owners cannot have shares in more than one club and team must have a tournament squad of 26-35 players, with special transfer windows opened between June 1-10.

FIFA will judge any disputes between Club World Cup teams who each want to take the same player to the tournament.

The tournament straddles the June 30 date when player contracts typically expire -- as Kylian Mbappé's did when moving in July as a free agent to Real Madrid from Paris Saint-Germain -- and has forced FIFA to find solutions for new transfer issues.

Potential free agents at qualified teams include Manchester City playmaker Kevin De Bruyne, Bayern Munich trio Alphonso Davies, Joshua Kimmich and Leroy Sané, Inter Milan defender Denzel Dumfries and Madrid's Ferland Mendy.

Pending free agents can officially start talks in January with other clubs and reach agreements to sign for them next season.

However, the June 15 start of the Club World Cup is technically still this season and FIFA has given member federations the option of opening an exceptional transfer window from June 1-10 to push deals through.

It means players in Europe could play for one team in the Champions League final on May 31 and for a different team 15 days later at the Club World Cup.

FIFA also will let Club World Cup teams change their squad list mid-tournament, from June 27-July 3 to "replace players whose contracts have naturally expired."

However, players can represent only one team at the Club World Cup and would not be eligible to transfer and play for another in the second half of the tournament.

FIFA has yet to confirm tournament prize money or details of the tournament draw, which is expected early in December.

The 32nd and last entry, from South America, will be decided on Nov. 30 by the Copa Libertadores final between Brazilian teams Atlético Mineiro and Botafogo in Buenos Aires, Argentina.

Teams qualified by winning a continental club championship from 2020 to 2024, or were ranked highly by consistently good results in competitions. Countries were limited to two entries unless they had more than two title winners. Brazil will have four teams in the U.S. and Mexico will have three.

FIFA added Lionel Messi's club Inter Miami to the lineup last month to represent the host nation based on its regular-season record, rather than wait for the MLS Cup final on Dec. 7. Inter Miami will play in the opening game at the Miami Dolphins stadium.

Information from The Associated Press was used in this report.