UEFA are reportedly re-thinking the multi-country nature of the Euros after the tournament was postponed by 12 months due to the ongoing coronavirus pandemic.
A total of 12 host cities in 12 different countries were scheduled to host fixtures this summer before the global health crisis forced the competition's delay.
And UEFA are now concerned that a number of those cities will be reluctant to stage matches next year due to lucrative prior commitments, report the Daily Mail.
It is alleged the Spanish and Italian FAs have already privately expressed doubts over hosting games in Rome and Bilbao respectively given the impact coronavirus has had in those areas.
The FA reportedly remain committed to staging fixtures at Wembley - namely each of England's group games, both semi-finals and the final - but would need to cancel a number of money-spinning concert dates.
And other host venues around Europe, including Hampden Park in Glasgow, the Amsterdam Arena and Dublin's Aviva Stadium, have similar commitments.
UEFA chief Aleksander Ceferin is alleged to have never been sold on the idea of a multi-country tournament, the brainchild of his now disgraced predecessor Michel Platini.
The combination of his standpoint, the impact of coronavirus and scheduling clashes could see the number of host cities dramatically scaled back.
"Euro 2020 is foreseen to take place between June 11 and July 11, 2021, with the intention of having the same match schedule and the same host cities," a UEFA spokesman told the Mail.
"However, at this stage the match schedule has not been officially confirmed. UEFA is in contact with all 12 host cities and further announcements will be made."