On Sunday afternoon, it emerged that the winger had been surprisingly omitted from the group for the Premier League opener against champions Manchester City.
Head coach Enzo Maresca insisted that it was purely "a technical decision" and it has since been widely claimed that the 29-year-old has been informed that he should not expect regular game time this season.
With Chelsea facing a busy schedule over the next two weeks, the possibility remained that Sterling could have been provided with the opportunity to impress over the two legs against Swiss opposition.
Instead, it has been revealed that the England international is one of four high-profile names to have been left out by Maresca.
Who else will play no part of playoff tie?
Ben Chilwell finds himself in a similar position to Sterling in the sense that he, too, has been told that he is free to leave Stamford Bridge for the right price.
With Marc Cucurella nursing a hamstring injury or cramp late in the Man City game, the left-back could have plausibly been included as cover, but preference has gone to Renato Veiga.
Wesley Fofana successfully came through 90 minutes against City in what was his first competitive appearance for well over a year having recovered from a serious knee injury.
That means that it should come as no surprise that the centre-back is being rested, yet eyebrows will be raised that experienced new signing Tosin Adarabioyo has not been selected.
Axel Disasi and Benoit Badiashile - each of whom did not accumulate any minutes at the weekend - are the only two recognised central defenders named on the 'A' list, although Levi Colwill will be selected on the 'B' list in due course.
There is also a surprise place for Reece James who has been recovering from a minor hamstring injury and had been expected to remain absent.
Any other surprises?
Maresca has suggested that Carney Chukwuemeka needs '30 to 35 games' during 2024-25 having struggled for fitness over the past two seasons, the indication being that he will go out on loan.
Nevertheless, the playmaker is selected as part of a 21-player group, as his 18-year-old Marc Guiu after making his debut at the weekend.
Colwill and other academy players will also be available to Maresca for the first leg which takes place at Stamford Bridge on Thursday night.
Chelsea 'A' list in full
Goalkeepers: Sanchez, Jorgensen, Bettinelli;
Defenders: Disasi, Cucurella, Badiashile, James, Gusto, Veiga;
Midfielders: Fernandez, Madueke, Chukwuemeka, Nkunku, Palmer, Dewsbury-Hall, Caicedo, Lavia;
Forwards: Mudryk, Jackson, Neto, Guiu