Chelsea have already had an appeal rejected by FIFA and have now escalated the issue, although there has been no application for the ban to be frozen on appeal. That means that Chelsea will still not be able to register new players while the appeal process is ongoing.
To have the ban frozen, Chelsea would have to have made a separate application. That perhaps ties into a report that emerged earlier this week claiming there were concerns at Stamford Bridge that the ban could even be extended to three transfer windows if they try to delay it.
A CAS spokeswoman told The Sun, "For a challenged decision to be stayed during the CAS proceedings, a specific request to this effect must be made. At the time of writing, a request has not been filed in the Chelsea / FIFA matter. Accordingly, the FIFA decision remains in force."
It was mooted last month that Chelsea were delaying a request to freeze the ban as they weighed up their next move, taking into account the players at their disposal already and the availability of the specific players they to improve the squad this summer.
The general conclusion from reports at that time was that it might just be better to start serving the ban and get it over with, rather than delay it and still have to go through it at a later date anyway if the CAS appeal is ultimately rejected.
That would mean if Chelsea start the ban this summer while CAS is deliberating, they would at least already be halfway through it if the verdict sides with FIFA, rather than having to start in January and miss out on signing players in the summer of 2020 instead.
Chelsea are seemingly already making plans to cope without signing new players ahead of the 2019/20 campaign, with new contracts handed to David Luiz and Olivier Giroud, rumours of a possible new deal for Willian, and talk that Kurt Zouma and others who have previously spent time on loan at other clubs could be brought back in the first team picture.