Denmark were recovering on Friday after each player lost four litres of water playing in the scorching heat of South Korea in their World Cup group A 1-1 draw with Senegal.
The Danes top the group, also including world champions France and Uruguay, after the draw on Thursday. The match was played in sweltering conditions with temperatures reaching 30 degrees Celsius in the inland city.
Danish team doctor Mogens Kreutzfeldt said each player had lost four litres of water during the match and would take time to recover before their crucial clash with world champions France on Tuesday.
A point for the Danes would be enough to take them through to the last 16 while the French must defeat them by two goals to ensure they avoid the ignominy of becoming the first defending champions since Brazil in 1966 to go out in the first round.
Morten Olsen's side left the Taegu Stadium on Thursday physically as well as mentally shattered, complaining that Senegal, who cancelled out Jon Dahl Tomasson's early penalty with a 52nd minute equaliser from Salif Diao in a strong second half display, were far more used to the searing heat than they were.
"I can't imagine it could be any hotter. We're from the northern part of Europe and we are not used to heat like that," said Danish winger Jesper Gronkjaer.
Team mate Rene Henriksen added: "In heat like that we cannot play the way we want to. We just don't have the power."
Denmark had been upset before the Senegal clash when FIFA dismissed their protest at having to play the match in the early afternoon.
The game had originally been scheduled for a 2030 start but was switched because of television demands to broadcast France's match with Uruguay later in the evening.
"We said it was unfair to play an African team in the heat of the day but FIFA said the decision to switch was within the rules," a Danish team spokesman told Reuters.
"We told FIFA in our letter that we had bad experiences from the World Cup in France in 1998 when we played South Africa in Toulouse where it was even hotter than it was on Thursday.
"Our complaint was about the discrepancy between FIFA trying to promote fair play and then to make this change which we view as unfair to the Danish team.
"We don't find that these conditions will enable us to perform at a level that you can expect from a World Cup match."