Pompey begin their defence of the EFL Trophy with group games against Crawley and Oxford.
Kenny Jackett’s side will discover their third and final opponents when the draw for under-21 invited clubs is made – live on Talksport – at around 12.30pm on Friday.
It is the third year in succession that the Blues are in the same group as League Two side Crawley and they won both previous encounters.
Dion Donohue grabbed the only goal in the most recent encounter, securing top spot for Pompey, who went on to lift the trophy at Wembley.
They have not met fellow League One outfit Oxford in the competition since it was an all-knockout format in 2013, with Patrick Agyemang and John Marquis on target in a 2-1 victory.
The Blues will face one side at home and one away, while there will also be a Fratton fixture against one of the southern-based invited teams.
Sides finishing in the top two of each group qualify for the knockout stages, while drawn games will once again be followed by a penalty shoot-out, with a bonus point on offer.
Games are scheduled to be played in the weeks beginning September 2, October 7 and November 11, although there is some flexibility with these dates.
The 48 EFL clubs were placed into pre-determined groups, with consideration given to ensure travel time is minimised for supporters.
Invited clubs in the southern section include Arsenal, Brighton, Chelsea, Fulham, Norwich, Southampton, Tottenham and West Ham. Matches that require significant police presence will be avoided where possible.