It would have been a clash between the top two sides in League One had this fixture taken place as originally scheduled in November.
But despite Oxford slipping down to just outside the play-off places, John Mousinho still expects a tricky midweek test for his side at the Kassam Stadium.
He knows all about the hosts, of course, spending almost six years with United as a player before taking up his first head coach role on the south coast 12 months ago.
Mousinho is not focusing on his own return, however, and is more concerned with Pompey trying to collect a third successive win on the road.
The Blues boss said: “Oxford have had an interesting season with a change of manager – there have been in two in charge since we went there last season.
“They’ve been near the top of the table for most of the campaign and have just dropped down a bit recently.
“But they’re an excellent side and have got threats right across the board, including a few that I know a lot about. They can hurt anyone on their day.
"It’s a fairly local one, which is nice for the fans, and we’ll be doing everything we can to give them something to celebrate."
“For me, it’s just like any other game – it probably felt like there was a bit more fanfare when I went back last season. Now it’s just business as usual.
“We dominated the game at Port Vale for 90 minutes on Saturday and just struggled to put the ball in the back of the net.
“But the fact we came away from an away game with three points and our keeper not having a save to make, shows we’re in a positive place.
“Now it’s a fairly local one, which is nice for the fans, and we’ll be doing everything we can to give them something to celebrate.”
Pompey were without experienced skipper Marlon Pack at Vale Park after he felt ill on the morning of the match.
Mousinho said: “It was pretty nasty, but he’s okay. It’s probably touch and go for this game and it might just be a step too far.
“Joe Rafferty has returned to full training following his neck injury, though, and is available for selection again.”