Europe's top leagues have warned FIFA not to rush a decision on moving the 2022 World Cup in Qatar to the winter.
The world governing body is due to decide on a switch at a meeting on October 3/4, but the Association of the European Professional Football Leagues (EPFL) - which includes the Premier League - has called for this to be postponed pending a full investigation into the effects of such a move.
FIFA president Sepp Blatter revealed on Monday that he will recommend a switch to the winter and UEFA president Michel Platini also wants a change.
But the EPFL said in a statement: "The feasibility of any change to the calendar involves every aspect of football organisation across all countries, from the grass-roots to the major national representative tournaments and the leagues.
"Any suggestion of staging the World Cup at a time other than the traditional period is a crucial issue for the European Leagues considering the impact on the organisation of domestic championships throughout Europe, and of the international football calendar around the world.
"The EPFL is of the view that no hasty decision shall be made by the FIFA executive committee of October 3-4."
The statement adds "such an important decision cannot be rushed with artificial deadlines" and says a full consultation with all football stakeholders should take place, and a proper medical assessment of a summer World Cup in Qatar would affect players and fans.
The EPFL also want FIFA to look at the consequences a move may have on the transfer system, any effects on commercial and media contracts and possible effects on the amateur game.
Blatter has also has admitted for the first time that FIFA may have made a mistake when appointing Qatar as the host nation.
When it was suggested FIFA should have been aware that Qatar's climate would prevent a summer tournament taking place before they were voted as 2022 host in 2010, Blatter said: "That may well be so, and it may well be that we made a mistake at the time."