Gillingham are set to bring a bumper away following to Fratton Park on Saturday.
The Gills faithful have snapped up their 1,322 ticket allocation for the League One clash against Pompey.
As a result, the Blues have given the Priestfield outfield a further 200 - making the fixture an all-ticket affair.
If Gillingham sell out their additional allocation, it will means they'll bring the second-largest away attendance to PO4 this season.
On November 25, 1,870 Plymouth fans descended on Fratton Park but saw their side fall to a 1-0 defeat, courtesy of Kal Naismith's first-half goal.
Currently, Southend hold the second-largest away attendance this campaign.
On November 18, 1,422 of the Shrimpers faithful made the journey round the M25 but Brett Pitman's second-half header delivered Pompey a 1-0 victory.
When the two sides met at Priestfield in October, Kenny Jackett's troops clinched a 1-0 win over Gillingham.
Matty Kennedy was on target for the Blues one minute after the restart.