UEFA have sent a warning to leagues across Europe that the season must be finished by August 3.
Football across the continent has been shut down by the coronavirus pandemic, with Euro 2020 moved back a year to try and give time for domestic leagues to conclude.
UEFA had initially set a deadline of June 30 for domestic league and the Champions League and Europa League to be completed.
There is now an acceptance that won't be possible, but as the SPFL prepares to meet on Wednesday to find a solution a final deadline has been issued for continental competition.
That will affect Rangers and their second leg against Bayer Leverkusen, but is also likely to be the deadline to finish league games.
President Aleksander Ceferin told Zdf: "By August 3 everything must be finished, both for the Champions League and the Europa League.
"This is an extraordinary situation but we can play on the same dates as the domestic leagues.
"At the same time, we have to be flexible.
"If the crisis stops then we'll start earlier. We could play with the current system or also with straight knockout competition.
"That would either be a one-off game at the team that's been drawn at home or on neutral ground.
"The only wrong decision would be to play in a way that endangers the health of players, fans, referees. But if the conditions are safe, I don't see any problems."
