Whenever a player from one club joins another on loan, the rule is that they are ineligible to compete against their parent club over the course of the season.
Next Wednesday, the Blues will take on Derby County in the fourth round of the EFL Cup.
It will be a special tie for the West London outfit as they will be playing a side that are being managed by Frank Lampard.
The Chelsea legend took over at Pride Park in the summer and has recently learned that he will be able to field Mason Mount and Fikayo Tomori against the Blues.
The youngsters joined Derby on season-long loans from Stamford Bridge and Mount, in particular, has been impressing.
On Monday, Chelsea confirmed via their official website that Mount and Tomori have been granted permission by the club to play against them in the EFL tie.
On Reddit, plenty of supporters posted their thoughts on the news, and many are happy with the decision.