Climate change has increased the likelihood of temperatures high enough to affect player performance at 97 of the 104 tournament matches.
Morocco winger Nordin Amrabat has been discharged from hospital but he will not play in the side's next World Cup Group B clash against Portugal on Wednesday after suffering concussion in the 1-0 loss to Iran, officials said.
PSV Eindhoven, unbeaten in all competitions this season, cruised to a 3-1 win at Heerenveen in the Dutch Cup fourth round on Saturday.
Aziz Bouhaddouz headed an own goal in the fifth minute of stoppage time to give Iran a stunning 1-0 victory over Morocco in the first Group B game of the World Cup on Friday.
Real Madrid beat Leganes 2-1 in La Liga on Saturday after coach Zinedine Zidane heavily rotated his side in preparation for Tuesday's Champions League semi-final second leg against Bayern Munich, including leaving out top-scorer Cristiano Ronaldo.
Cristiano Ronaldo powered-home a fourth-minute header to give Portugal a 1-0 World Cup victory over Morocco that took them top of Group B on Wednesday and meant the unlucky North African side become the first to be eliminated from the tournament.
Spain snatched a 2-2 draw against Morocco on Monday to qualify for the World Cup last 16 and take top spot in Group B ahead of Portugal on goals scored.
Free-scoring Arsenal replaced Chelsea as Premier League leaders as goals either side of halftime by Theo Walcott and Mesut Ozil helped them recover from a slow start to beat Stoke City 3-1 on Saturday.
The 2-2 draw in Kaliningrad was thrilling for neutrals but exposed huge vulnerabilities in the 2010 world champions, who had to come from behind twice after careless mistakes gifted two goals to already-eliminated Morocco.
Marcelino dismissed but Valencia keep pressure on Barcelona
Villarreal went top with a 1-0 win over Atletico Madrid on Saturday after a toothless Real Madrid were held 0-0 at home to 10-man Malaga and Lionel Messi suffered a serious injury as Barcelona beat Las Palmas 2-1.
Real Madrid and Atletico each slipped 10 points behind La Liga leaders Barcelona after an intense Madrid derby finished goalless and the Catalans picked up an 11th victory in 12 games by winning 3-0 at Leganes.
The stability and pragmatism of Carlos Queiroz's seven-year reign has firmly established Iran's as Asia's number one team, but the nation will go to the World Cup hoping to advance for the first time to the knockout phase.
Real Madrid returned to winning ways after last weekend's drubbing at Atletico but failed to convince and were whistled by their own fans during a drab 2-0 victory at home to Deportivo La Coruna on Saturday.
