Nearly 1000 travelling members of the Fratton faithful will descend on the Keepmoat Stadium tomorrow.
Pompey fans have snapped up around 900 tickets so far for the League One clash against Doncaster Rovers.
And tickets can still be purchased at the Keepmoat Stadium tomorrow.
Blues supporters will be rallying behind Kenny Jackett’s troops as they bid to equal the best-ever start to a league campaign in the club’s history.
Pompey are aiming to continue their perfect opening to the season against Donny following wins over Luton, Blackpool, Oxford United and Bristol Rovers.
A fifth-straight success would see the Blues equal the record set by Frank Burrows’ men in the 1979-80 campaign.
Meanwhile, tickets for Pompey’s Checkatrade Trophy clash against Gillingham on Tuesday, September 4 are on general sale.
Only the South Stand Upper and Nelson’s Family Zone will be open, while season ticket holders’ seats are not reserved.