Liverpool manager Jurgen Klopp and Manchester United boss Ole Gunnar Solskjaer have questioned the feasibility of players having to spend 10 days isolating in a hotel after returning from World Cup qualifiers in countries on the UK's COVID-19 Red List.
Direct travel to and from Red List countries is banned in the UK, with the whole of South America and Portugal still under those strict measures. Liverpool have three Brazil internationals -- Alisson, Fabinho and Roberto Firmino -- and Portugal forward Diogo Jota all likely to be called up by their countries later this month.
Anyone that returns from countries on the Red List must quarantine in an airport hotel for 10 days, with no exemptions for elite athletes, and Klopp admitted his concern about the potential impact of players flying around the globe for the World Cup qualifiers.
"Having more information would be great, but we don't get the information," Klopp told a news conference on Wednesday. "I think that FIFA was kind of clear, saying we don't have to let the players go this time and I think all the clubs agree that we cannot just let the boys go and solve the situation when they come back, with our players having a 10-day quarantine in a hotel or whatever.
"That is just not possible. I understand the need of the different FAs, but this is a time when we cannot make everybody happy. So we have to admit that the players are paid by the clubs, which means we have to be first priority. That's how it is.
"It means we all have understanding for different needs, with competitions coming up in the summer, I get it. But you cannot make everybody happy at the same time in this period of our lives.
"People need time to make decisions and we don't think too much about it because we are not influential in it, but we just deal with things other people decided.
"But I think everybody agrees -- we can't let the players go and play for their country and then quarantine for 10 days in a hotel. That's not how we can do it."
"We've not sat down and made a proper call on that one but it doesn't make sense if you lose your player for 10 days of isolation, of course it doesn't," Solskjaer said.
"We're the ones paying the players and from what I understand FIFA have given the rules that they don't have to be released. So I would think that's going to be a hard call to make to let them go and play in red list countries, yeah."
Among the players United could lose to isolation would be Portugal midfielder Bruno Fernandes ahead of crucial Premier League clashes.
"I want Bruno of course, ready against Brighton and hopefully that we are through in Europe and against Tottenham after that break, of course I do," Solskjaer added.
But with FIFA giving clubs permission to withhold players for this round of qualifiers in the event of COVID-19 issues, Klopp has said that the interest of clubs must come first.
The COVID-19 infection rate in the UK has dropped in recent weeks to the extent that the government has now laid out a roadmap towards the relaxation of social distancing measures, with all restrictions due to be lifted by June 21.
But despite the progress in the UK, Klopp said that clubs are concerned about the prospect of players leaving their COVID-19 secure bubbles to join up with their international squads.
"First and foremost, we are concerned, yes, about all the things which happened from a virus point of view in the last few months, when somebody had to leave the bubble," he added. "Within the bubble, we were not without cases, but we have been without cases for a long time now and it never spread.
"There were two periods -- in the last international break, when more cases came up than before and the Christmas period, which was a challenge for all of society.
"And now in England, it is all going in the right direction and looks positive and promising, but yes we are concerned about things."
CONMEBOL will meet internally on Wednesday and have a virtual meeting with FIFA president Gianni Infantino planed for Thursday to discuss the issue.
Sources have told ESPN that CONMEBOL leaders are not considering playing in a bubble, and will not play the qualifiers without their European players.
ESPN's James Olley contributed to this report.