Millwall will be at home to Portsmouth in the Carabao Cup First Round.
The two clubs will meet at The Den after being paired in Thursday's draw.
It will be a first fixture between the duo in nine years, since Harry Kane's goal won a Sky Bet Championship match for The Lions at Fratton Park in April 2012.
Matches are scheduled to take place in the week commencing 9th August, however, clubs are able to mutually agree an alternative date between 31st July and 4th August.
Further details, such as a confirmed date, kick-off time and more, will be announced in due course.