Pompey will face Southend United in the third round of the Checkatrade Trophy.
The Blues will travel to Roots Hall for the game on the week commencing January 7, 2019.
Pompey booked their place in the third round with a 2-1 win against Arsenal under-21s on Tuesday night.
Brett Pitman and Andre Green scored in the victory over the north London side.
The Blues face Southend, who beat Luton on penalties in the last round, today in League One at Fratton Park.