Pompey have been drawn away to Walsall in the third round of the Leasing.com Trophy.
The Southern Section tie will take place at the Bescot Stadium in the week beginning January 6.
It will be the first time the sides have met in any of the competition's guises, although Pompey won both League One clashes last term.
Walsall were relegated at the end of the campaign and Darrell Clarke's men currently sit 22nd in the fourth tier.
But they beat Southampton's youngsters on their way to topping Southern Group D of the Leasing.com Trophy, then battled from two goals down to see off Chelsea U21s in the second round on Tuesday night.
Walsall have never lifted the silverware, but did reach the final in 2015, losing 2-0 to Bristol City at Wembley.
Pompey are, of course, the competition holders, having beaten Sunderland on penalties at the national stadium last season.
A confirmed date for the fixture and ticket information will be announced in due course.
|Leasing.com Trophy Round Three – South|
|Walsall v POMPEY|
|Bristol Rovers v Stevenage|
|Newport County v Milton Keynes Dons|
|Exeter City v Ipswich Town|
|Leasing.com Trophy Round Three – North|
|Salford City v Port Vale|
|Scunthorpe United v Manchester City U21|
|Tranmere Rovers v Leicester City U21|
|Fleetwood Town v Accrington Stanley or Bolton Wanderers|