The Blues currently sit third in the League One table – four points behind leaders Luton and second-placed Barnsley but with a game in hand.
Kenny Jackett's side will catch up on matches played when they host Peterborough at Fratton Park tonight.
The game also offers the opportunity to significantly close the gap on the top two ahead of what promises to be a nerve-wracking final day of the season on Saturday.
All three teams could still be crowned League One champions at the weekend, while one and possibly two could miss out on automatic promotion altogether with Sunderland still mathematically in the mix, although the likelihood of that happening remains remote.
While the Blues face Accrington at PO4 on Saturday, Luton play host to Oxford, with Barnsley facing a trip to Bristol Rovers, who retained their place in the division following their draw at Fleetwood last time out.
Pompey defender Brown spent seven years at Rovers, racking up more than 300 appearances before moving to Fratton Park on a free transfer last summer.
He’s still in touch with team-mates at the Memorial Stadium.
And according to defender Tom Lockyer, the left-back has been in touch looking for the Gas to get one over the Tykes.
Speaking to the club website, Lockyer said: ‘Browny's already been on the messages to me saying 'come on, do us a favour'.
‘It's not a case of the season's done now, we've got a game to go.
‘Obviously it will be nice to enjoy it without pressure and it will be nice for the fans to enjoy it without pressure.
‘At the end of the day we want to finish the season on a high and that will be trying to beat Barnsley.’