Liverpool may stop their international players from travelling to World Cup qualifiers later this month after Jurgen Klopp insisted a 10-day quarantine was not possible.
Brazil want to call up Alisson Becker, Roberto Firmino and Fabinho for their fixtures against Colombia and Argentina; the whole of South America is currently on a red zone and direct travel to Brazil is prohibited from the UK. There are no exemptions for professional sportsmen.
Portugal is also in that severe tier but they would want Diogo Jota to be part of their squad for their opening game in Lisbon against Azerbaijan on March 24; Sadio Mane's Senegal are due to play Congo and Eswatini, while Guinea, for whom Naby Keita plays, are set to face Namibia.
Jurgen Klopp has risked a club-versus-country row by saying any Liverpool players who represent countries on the UK's Covid red list won't be allowed on international duty
Liverpool's Brazilian goalkeeper Alisson Becker could miss two World Cup qualifiers
Fabinho (left) and Roberto Firmino (right) could also be forced to miss Brazil duty this month
Given the current travel restrictions, those six would have to isolate in a hotel for 10 days upon their return, which would rule them out of crucial Premier League fixtures against Arsenal and Aston Villa plus a potential Champions League quarter-final first leg.
There are 33 nations currently on the Government's Covid-19 red list, meaning anyone who enters the UK from there must legally quarantine in an approved hotel room for 10 days.
Despite the risk of igniting a club-versus-country row, Klopp made absolutely clear that no Liverpool players will be allowed away for international duty if they have to quarantine on their return.
Speaking ahead of Thursday's Premier League meeting with Chelsea, Klopp said: 'I think all the [Premier League] clubs with the same problems agree we cannot just let the boys just go and then sort the situation when they return with a 10-day quarantine in a hotel or whatever. That is just not possible.
Portugal's Diogo Jota is another who would be affected with his country on the red list
Current UK Covid-19 red list
Democratic Republic of the Congo
Portugal (including Madeira and the Azores)
United Arab Emirates (UAE)
Anyone who has been in or travelled through any of these countries 10 days prior to arriving in the UK will be refused entry.
Any UK nationals or residents travelling into the country from these countries must quarantine for 10 days in a Government-approved hotel.
'I understand the needs of the different FAs but this is a time when we cannot make everybody happy.
'We have to admit that the players are paid by the clubs so that means we have to be the first priority. That's how it is.
'I get the need with the 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.
'Everybody agrees, we cannot let the players just go and have them come back and stay in a quarantine for 10 days in a hotel. That is not how we can do it.'
Speaking about the wider Covid situation and how the club had dealt with it, Klopp said: First and foremost, we are concerned yes about all the things which happened from a virus point of view in the last few months.
Liverpool players Roberto Firmino (left) and Alisson Becker (right) playing for Brazil
'When someone had to leave the bubble, we weren't without cases the whole time, but it never spread it was one case and self-isolation and come back again.
'But during the last international break there were more cases than before that came up and Christmas period, like the whole society, that was a challenge for us.
Liverpool fixtures after March internationals
Dates and times TBC; Premier League unless stated
April 3 Arsenal (A)
April 6/7 Possible Champions League quarter-final, first leg
April 10 Aston Villa (H)
April 13/14 Possible Champions League quarter-final, second leg
April 17 Leeds United (A)
'Now in England it is going in the right direction, it looks positive and promising. Yes, we are concerned about these kind of things.
'The only problem I have is - what is a red list country? England is doing really well but we are on the red list for some other countries.
'It is not easy for us to travel from England. Any more info would be nice. The FIFA boss was kind of clear that we don't have to let the players go this time.'
CONMEBOL leaders, who run the South American game, are not considering playing in a bubble. But they will not play the qualifiers without their European players, so they could potentially postpone the fixtures.
They are due to have a virtual meeting with FIFA president Gianni Infantino today.
Last month, FIFA created an exemption for clubs releasing players for International duty this month.
Clubs are usually bound by FIFA regulations to release players but amid the pandemic the rule has been changed so they are no longer obliged to let players go if a mandatory quarantine period of five days or more is expected on their return.
FIFA said in a statement: 'In the context of the challenges that remain in place for both international and domestic football due to the COVID-19 pandemic, the Bureau of the FIFA Council has decided to provide additional flexibility regarding the release of players for national team duty and the registration of players with clubs in competitions that remain disrupted by the pandemic.'