Chelsea may be forced to leave any players not vaccinated against coronavirus at home for the second leg of their Champions League last-16 tie against Lille in March.
France has toughened its Covid rules and there is now no exemption for unvaccinated professional athletes wishing to enter the country.
European football’s governing body Uefa released a statement on Thursday morning saying that teams would be required “in principle” to abide by applicable rules in any country.
Uefa is yet to publish its updated regulations for the knockout phases of its three men’s club competitions, which it says will provide “further guidance”.
French president Emmanuel Macron has previously stated he wants to “p*** off” unvaccinated people by limiting their access to public places such as bars, cinemas and restaurants.
It seems unlikely Uefa – whose president Aleksander Ceferin has emphatically stated his support for vaccination – would undermine the French approach by insisting on matches being moved to a neutral venue to get around the rules.
Any unvaccinated Chelsea players or staff are therefore expected to be treated as though they have tested positive for Covid, and be barred from travelling for the second leg on 16 March.
The Premier League is consulting with clubs over changes to the Covid-19 postponement criteria in the wake of falling case numbers among clubs and in the wider population.