The Blues had a fruitless trip to Crewe on Saturday following a controversial calling off on the grounds of a waterlogged pitch.
However, this evening’s encounter with Steve Cotterill goes ahead, with the playing surface seemingly in excellent condition.
O’Brien represents one of four changes to the side which won 4-0 against Doncaster in Pompey’s last outing, having netted with his first touch after coming off the bench.
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He replaces the injured Michael Jacobs, while Marcus Harness, Reeco Hackett and Tyler Walker drop to the bench.
Mahlon Romeo, Ryan Tunnicliffe and Denver Hume join O’Brien in the starting XI.
For Tunnicliffe, it’s a first start since damaging his hamstring against Bolton at the end of October.
Meanwhile, Jay Mingi is involved in a Pompey squad for the first time, having been named on the bench.
Pompey: Bazunu, Carter, Raggett, Robertson, Thompson, Tunnicliffe, Romeo, Hume, Curtis, O’Brien, Hirst.
Subs: Webber, Ogilvie, Jewitt-White, Mingi, Hackett, Harness, Walker.
A message from the Editor, Mark Waldron
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