Pompey held off MK Dons to book their place in the third round of the Emirates FA Cup.
A 3-2 victory ensured they would join Premier League and Championship clubs in Monday night's draw.
Darragh Burns gave the visitors the lead against the run of play, but Reeco Hackett hit an immediate equaliser.
A brace of Colby Bishop spot-kicks put Danny Cowley's side in charge, ensuring that Mo Eisa's effort for the Dons proved no more than a consolation.