Marlon Pack, Joe Rafferty and Tom Lowery are all itching to get back into the starting XI following time spent on the sidelines.
Meanwhile, Dane Scarlett will want his place back after Joe Pigott was favoured for the trip to Gloucestershire.
Form will no doubt also be taken into consideration when manager Cowley ponders his options ahead of the U’s game.
But what will he decide for such a crucial fixture?
As always, only Cowley and his coaching team know the answer to that question.
But here’s how we think the Blues could line up for tonight’s game at Fratton Park.
1. Josh Griffiths - goalkeeper
The West Brom keeper has had his critics - unfairly in some people's eyes - but he rarely lets Pompey down. Will continue to be the Blues' No1 unless the Baggies, under a new manager, demand him back Photo: Jason Brown
2. Joe Rafferty
There's a tough call to make for Danny Cowley at right-back. Does he stick with youngster Zak Swanson, who impressed on his full league debut at Forest Green? Or does he turn to the experienced Joe Rafferty, who is available again after stomach surgery. It would be harsh to drop Swanson but you suspect Cowley might reinstate the former Preston man given Oxford's attacking threat. Rafferty's fitness will not be much of a concern either, given we've been told he has been training in recent weeks. Photo: Jason Brown
3. Sean Raggett - centre-back 1
It's going to take one hell of a player to shift Sean Raggett from Pompey's starting XI - and let's face it, there's no-one else currently at Fratton Park to do that. Kenny Jackett, erm, we salute you! Photo: Jason Brown
4. Clark Robertson - centre-back 2
The club captain reverted back to his more familiar left centre-back role at Forest Green and did well. You suspect his partnership with Sean Raggett might be Danny Cowley's preferred option going forward, especially with his ability to play out from the back and deliveries from set-pieces. Photo: Jason Brown