While it’s normal for parent clubs to not let their players compete against them when on loan, Chelsea have made the move to allow the duo to be involved.
Lampard’s status as Derby’s manager no doubt played a huge role in that decision.
The England international is a legendary figure in west London having won the Champions League and Premier League with the English giants.
And Chelsea released a statement confirming that Mount and Tomori are eligible to be involved.
The statement read: ‘Chelsea Football Club has today granted Derby County permission to select loanees Mason Mount and Fikayo Tomori for next week’s Carabao Cup fourth-round fixture.
‘Unlike in the Premier League, EFL Cup rules allow for clubs in the competition to make such agreements for players to appear against their parent clubs.
‘Mount and Tomori have been regulars for the Rams under Frank Lampard this season, and, after beating Manchester United at Old Trafford in the previous round, we believe the experience of facing top-level opposition once more will be of benefit to their on-going development at Derby.’
Derby took out Manchester United in the previous round and Chelsea fans will be hoping their decision won’t come back to bite them.