UEFA have been keeping Russian and Ukrainian teams apart so far this season, due to the conflict in eastern Ukraine.
However, with Dynamo Kiev, Dnipro and Zenit St Petersburg all in quarter-final second leg action tonight,
the BBC say the governing body may need to step in should all three progress.
If that does happen, Dynamo Kiev will play Dnipro in the last four, while Zenit will face the winners of Napoli's tie against Wolfsburg, with the Italians leading 4-1 on aggregate.
As it stands, Zenit trail reigning champions Sevilla 2-1 after their first leg, but the Russians do bring an away goal into this evening's return fixture.
Dnipro are home to Club Brugge in their second leg with the tie scoreless, while Dynamo Kiev travel to Florence to take on Fiorentina level at 1-1.
Dnipro at just short of evens to qualify for the last four, Zenit are 13/8, while Dynamo Kiev have the longest odds, at around 11/5.
However, should a Ukranian and Russian side meet in the final, it will go ahead as planned, with the National Stadium in Warsaw hosting the final on May 27.
Odds courtesy of
Ladbrokes
