Chelsea boss Thomas Tuchel has echoed the concerns of several other high-profile managers as he discussed the potential problems associated with players leaving on international duty in March.
Currently, the UK Government requires anyone returning from a trip to a 'red-list' country to quarantine for 10 days, with many Premier League stars set to head off abroad to link up with their national teams.
Included on the red list is Portugal, large parts of Africa and the whole of South America, and with that potentially seeing the likes of Thiago Silva and Edouard Mendy unavailable for a spell, Tuchel has suggested he could block players from leaving.
What's been said?
"I am absolutely worried because my target is to play in the Premier League and if I have players in quarantine, I cannot build the group that we want," Tuchel said after his side's 1-0 win over Liverpool on Thursday.
"This is the risk and I am absolutely worried about this situation. But I am also sure that the club knows how to handle it. If it maybe is the consequence that the players cannot go then this is the consequence.
"This situation is extraordinary. We have to adapt and we will do this as a club and we will make these decisions. We are very concerned about the situation."
What has FIFA said?
FIFA has given power back to the clubs to block players leaving in response to the ongoing concerns around the Covid-19 pandemic around the world.
If teams are subject to losing players for five days or more through quarantine rules, they can stop them from travelling. In such instances before the coronavirus outbreak, they would have had no choice but to allow their stars to leave.
As well as United midfielder Fernandes, Manchester City forward Bernardo Silva and several Brazilian players, including Ederson and Gabriel Jesus, Everton star Richarlison and Liverpool attacker Roberto Firmino are among those who could be affected.