Pompey will take their biggest away following of the season to MK Dons next month.
The Blues have sold 4,100 tickets for the League One clash on February 10 (3pm kick-off) – and have been handed 900 more.
Pompey’s biggest away trip this campaign was their league visit to Charlton on December 9, with 3,870 fans making the journey to the Valley for the 1-0 victory.
Yet that has already been trumped by the Blues’ upcoming trip to Stadium MK.
Last week, 3,000 tickets were purchased for the visit to the Dons, with half of those being bought within 24 hours of them going on sale by season-ticket holders and shareholders.
MK Dons gave Pompey 1,000 more and they have subsequently been snapped up by the Fratton faithful.
Stadium MK has a maximum capacity of 30,500 – although their average gate this term is just 8,906.
Coventry have sold their entire allocation of 7,883 tickets for their FA Cup fourth-round tie at the Dons on Saturday.
Meanwhile, the record away attendance at MK Dons was in March 2014 when 8,800 Wolves supporters descended on the stadium.