The EFL have confirmed Northampton's Leasing.com Trophy match with Portsmouth will kick-off at 7.45pm on Tuesday, December 3.
It means the Cobblers will play two games in the space of just over 48 hours with their FA Cup tie against Notts County scheduled for 2pm the Sunday before.
They also have a trip to Exeter City in the league the following Saturday, making for a busy six days for Keith Curle's side.
Portsmouth, who are the EFL Trophy holders having beaten Sunderland in the final last season, will host the tie at Fratton Park after topping Southern Group B.
Ticket prices have been reduced to £10 for adults, £5 for concessions (senior 65+, young person 18-22, wheelchair and ambulant) and £2 those 17 and under.
The club will confirm when ticket sales will begin in due course.