Just less than 3,000 fans will make the mammoth 676-mile round trip to the Stadium of Light for Pompey’s League One clash against the Black Cats on Saturday, April 27.
However, the Blues are being handed an additional 266 seats which go on sale this Wednesday (9am).
Pompey fans were queuing up in the rain to get their hands on tickets for the longest away-day of the season at the club’s Anson Road ticket office yesterday.
The clash could prove pivotal in the race for automatic promotion this term.
Kenny Jackett’s troops sit fourth in the table with seven games remaining.
Sunderland are two points and one place ahead following their 3-0 win over Accrington on Wednesday, while they still have a game in hand.
The Stadium of Light meeting will be a repeat of Sunday’s Checkatrade Trophy final.
It was Pompey who claimed the silverware at Wembley on penalties, following a 2-2 draw after extra-time.
The Blues are also taking 1,800 fans to Wycombe tomorrow, while their entire allocation for the Good Friday trip to Burton is also sold out.