The promising centre-back played for the Blues in the previous round of the Checkatrade Trophy during the win against Arsenal at Fratton Park on Tuesday, December 4.
He's been having a good spell on loan at Gosport Borough in the Southern League premier division south as well.
Now after getting the call to link back up with Pompey again the 19-year-old will miss Gosport's next two matches, including the trip to Poole on Saturday.
With Lee Brown and Nathan Thompson both out injured the Blues are a little short of defensive options at this busy time.
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The match against Norwich on Saturday in the FA Cup is quickly followed by Tuesday's trip to Southend in the Checkatrade Trophy (7.45pm).
Having been involved against Arsenal it could mean Jackett is considering playing Casey in the heart of the defence again.