Liverpool, Arsenal and other Premier League clubs will be without some of key their players for a crucial chunk of next season after plans to move the Africa Cup of Nations back to a January start date were approved.
European clubs were often critical of the decision to host the tournament in January and February, leading to a change in the format after the 2017 tournament.
Last year's finals were held in Egypt over the summer, with Riyad Mahrez's Algeria beating Sadio Mane's Senegal in the final, but after just one summer tournament a switch back to the beginning of the year has been agreed for for 2021 in Cameroon.
The issue was discussed on Wednesday, with Confederation of African Football president Ahmad Ahmad believed to be the major force in favour of the move.
Earlier on Wednesday, BBC Sport journalist John Bennett tweeted that the switch could occur because of the weather in Cameroon during June and July, which is traditionally rainy season, as well as FIFA's plan for the 2021 Club World Cup, which would take place in the summer.
The decision to move the tournament back to the European winter comes as a huge blow to several clubs, many of whom thought they had seen the back of the January-February AFCON after Gabon in 2017.
Liverpool could potentially be without two of their star front three in Egypt's Mohamed Salah and Senegal's African Footballer of the Year Mane for up to six matches, with Guinea's Naby Keita also potentially absent.
Arsenal could also be missing Pierre-Emerick Aubameyang should he choose to play for Gabon at the tournament, while Nicolas Pepe would also feature for the Ivory Coast.
Manchester City's Algerian star Mahrez and the Ivory Coast trio of Crystal Palace's Wilfried Zaha, Tottenham right-back Serge Aurier and Manchester United's Eric Bailly could also be called up.
