Scotland's national clinical director is confident Hampden Park will be able to accomodate fans for four Euro 2020 matches in June.
Glasgow is one of 12 cities due to host the tournament that was delayed 12 months due to the coronavirus pandemic.
UEFA have given the hosts until April 7 to notify them on what percentage of supporters will be allowed to attend matches with Covid-19 restrictions on large crowds still in place across the continent.
Professor Jason Leitch said it is highly likely that numbers will be capped to maintain social distancing requirements, but that some fans should be allowed in barring major setbacks in Scotland's route out of lockdown.
Other than a small number of trial events, no fans have been permitted in Scottish stadiums since March 2020.
Scotland are due to play two of their group matches against the Czech Republic and Croatia at Hampden in their first major international tournament for 23 years.
Croatia and the Czech Republic will also clash at Hampden before a last 16 tie on June 29.
"There are a number of scenarios UEFA, the SFA (Scottish Football Association) and the government are working on," Leitch told BBC Scotland.
"There are a variety of scenarios from basically zero to half the crowd, or even more than that. I think the most likely is somewhere between those two extremes by the time we get to June."
Under the British government's roadmap out of lockdown, up to 10,000 fans could be allowed to return to English stadiums by May 17 with restrictions on all social contact set to be lifted on June 21.
That could see full crowds return in time for England's final group game against Croatia at Wembley on June 22.
Wembley will also host a last 16 tie, both semi-finals and the final.
"I think with a fair wind - with good restrictions now - if people follow them, we will have crowds in Hampden and other UK stadia in June," Leitch added
"I'm not sure that will look normal. I think it may well be limited and distanced.
"I actually think UEFA will be more worried now about France, Belgium, Germany, some other countries where their virus is accelerating rather than decelerating, and that should be a warning to all of us."