Pompey have sold their initial allocation of 4,000 tickets for the trip to MK Dons on Sunday, December 29.
But supporters can still secure a seat for the League One contest at Stadium MK, which kicks-off at 3pm.
Tickets are no longer available to buy from the Blues, with fans needing to contact the home club or pay on the day.
They can call the MK Dons ticket office on 0333 200 5343 (open until 5pm on December 23, from 9am-2pm on Christmas Eve and from 9am-5pm on December 27).
Supporters can also visit the away booth (cash only) or ticket office from 9am on the day of the game.
Collections can also be made from the away booth, which is located at Gate Three.
*With a full-paying adult
Supporters buying concession tickets are advised to bring proof of age identification with them to the game.
Official coach travel can be purchased online here or by calling Lucketts Travel on 01329 237000.
Tickets are still available for Pompey’s trip to Gillingham on New Year’s Day (3pm kick-off), with around 900 already sold. Click here for more details.