Chelsea will not allow Frank Lampard permission to select loanees Mason Mount and Fikayo Tomori for Derby's trip to Stamford Bridge in the fourth round of the Carabao Cup, Goal understands.
The Blues legend returns to the capital as manager of the Championship club in what will be a special occasion for him personally, having spent 13 years of his playing career in west London.
Lampard's Chelsea connection will no doubt have helped him seal loan deals for the pair, two of the London club's brightest academy products, but EFL rules restrict the use of loanees against parent clubs without written consent.