The on-loan midfielder is expected to come straight back into the team to face Rotherham as the U’s try to end their run of five straight league defeats.
If Forster-Caskey does return, Wilder must decide which system to play.
Tony Capaldi filled the unfamiliar role on the left of a three-man midfield against Bradford, but could return to left back at the expense of Luke O’Brien.
However, Wilder may choose to go with a 4-4-2 system, which would see Capaldi on the left flank, Alfie Potter on the right, with Lee Cox and Forster-Caskey central.
Rotherham this week signed left-back Bob Harris on loan from Blackpool and he goes straight into the squad.
Kari Arnason has recovered from a foot injury and is likely to come straight back into the side.
He can play either in central defence or as a holding midfielder.
David Noble is also set to return, but Alex Revell misses out after his red card in last week’s 0-0 draw at Barnet.
Rotherham: from Shearer, Tonge, Sharps, Morgan, Taylor, O’Connor, Bradley, Pringle, Rose, Odejayi, Agard, Ainsworth, Warrington, Mullins, Hunt, Evans, Nardiello, Arnason, Noble, Harris.
Oxford Utd: from Clarke, Batt, Raynes, Wright, O’Brien, Potter, Cox, Forster-Caskey, Capaldi, Constable, Craddock, Smalley, Rigg, Heslop, Worley, Marsh, Brown, Leven, Boateng.