After a World Cup described by FIFA as the best ever, the true impact of its unprecedented calendar scheduling remains to be seen.  Staged in November and December for the first time in its 92-year history, the World Cup's aftermath will worry Europe's biggest football clubs.  "We are exhausted," Croatia midfielder Mateo Kovacic said Friday. "Many of us will be exhausted when we come back to our clubs."  Not exactly the news his club, Chelsea, will want to hear as it prepares for the resumption of the Premier League on Dec. 26. And Kovacic still has to get through the third-place match against Morocco on Saturday.  Morocco captain Romain Saiss will miss that match after being injured in his country's semifinal loss to France. Noussair Mazraoui, also substituted in that game, is a doubt.  "We have really, really pushed our players to the limits," Morocco coach Walid Regragui said.  Saiss plays for Turkish club Besiktas, which is back in action on Dec. 25.  The disruption caused by placing the World Cup during the European season has long been a bone of contention. Traditionally held in June and July, the tournament dates had to be moved because of Qatar's soaring temperatures at that time of the year.  The shift forced the club calendar to be reorganized, with extra games crammed into the first three months of the season and a congested schedule for the remainder of the campaign.  The biggest Premier League clubs, like Manchester City and Liverpool, will have to contend with the resumption of the Champions League and the start of the FA Cup, while also trying to catch up on the effects of a month without soccer.  That could lead to a strain on players who have already had to compete in the sport's biggest tournament.  "Their clubs might have some problems," Croatia coach Zlatko Dalić said. "Specifically the players who played until the end or almost the end.  "For 25 days we have been here and Morocco as well, so it will be a problem for club football."  With that in mind, City and Liverpool could be grateful for the fact neither of their star strikers, Erling Haaland or Mo Salah, respectively, qualified for the tournament in Qatar.  England, Spain, Italy and France all return to domestic action around the turn of the year, but the German league will take a break until Jan. 20.  Players are generally given about two weeks off after major tournaments and are likely to be given a break before being asked to play for their respective clubs. That could have an impact on Paris Saint-Germain, for example, with Lionel Messi and Kylian Mbappe both playing in Sunday's final between Argentina and France.  Manchester United's starting central defenders Raphael Varane and Lisandro Martinez, are involved, too.  Real Madrid, Juventus, Barcelona and Bayern Munich are all well represented among the finalists.  One positive for the leading clubs has been the success of underdogs Croatia and Morocco, who, between them, knocked out some of the tournament favorites in Belgium, Spain, Portugal and Brazil.  But their runs have still meant star players like Real Madrid's Luka Modric, PSG defender Achraf Hakimi and Bayern Munich defender Noussair Mazraoui have remained involved until the penultimate match of the World Cup.  "When we look at this World Cup, the greatest benefit was drawn by smaller teams because their players came in midseason in optimal form," Dalić said. "They were fit and prepared. When it comes to that aspect of the timing all national teams have benefited, specifically the smaller national teams."  The World Cup is set to return to its usual June-July period in 2026 when the tournament will be played in the United States, Mexico and Canada.   "There is another argument for a winter World Cup," said David Dein, a former vice chairman of the English Football Association who believes the tournament in Qatar has been a success. "I know managers won’t like it because they will lose their players at a critical time, but for the World Cup itself as a tournament, the players are fresher. There is no doubt.  "Since I’ve been involved in football we’ve always got club versus country going on," Dein said. "From FIFA’s point of view, there is a serious argument."