If Metalist follow a similar path, European soccer's governing body UEFA could be left with a logistical nightmare to sort out.
The decision by UEFA's appeals committee to expel the Ukrainian club came 10 days after Metalist lost an appeal at CAS over a domestic match-fixing case dating back to 2008.
Together, the two cases have created a bewildering number of possible scenarios that UEFA would have to deal with.
Fenerbahce have already beaten Austrian side Salzburg and face Arsenal over two legs in the final playoff round later this month, with the winners going into the group stage.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
CAS has said it will make a final ruling on Fenerbahce's case "by August 28", the day after the second leg.
That opens the possibility that Fenerbahce could qualify for the group stage, having eliminated both Arsenal and Salzburg, only to be expelled.
UEFA could simply award Fenerbahce's place to Arsenal, however that is almost certain to infuriate the Austrian side and their owners Red Bull, who have been trying in vain to reach Europe's elite competition since taking over the club in 2005.
On the other hand, there are no dates available in the international calendar to squeeze in a two-leg playoff between Salzburg and Arsenal, which would be the other option.
Metalist were due to face Schalke 04 in the playoff round but UEFA's emergency committee decided later on Wednesday that their place would be taken by PAOK, the Greek side they knocked out in the previous round.
However, UEFA did not address the possibility that Metalist could appeal to CAS and be re-admitted pending the final decision, as Fenerbahce were, possibly before the Schalke tie.
Metalist could also be re-admitted by CAS but then ultimately lose their appeal with the possibility that the final ruling might come after some group-stage matches have already been played.
Two years ago, UEFA was forced to draw up a number of contingency plans for reorganising the Europa League after Swiss club Sion launched a legal challenge over their expulsion from the competition over ineligible players.
These included increasing one of the groups from four to five teams to accommodate Sion and playing the additional fixtures during the winter break.
In the event, Sion lost their case and UEFA were spared a huge headache.
(Reporting By Brian Homewood; Editing by Sonia Oxley)
