Oxford boss Chris Wilder will hand Simon Heslop a late fitness test ahead of the home clash with league-leaders Chesterfield.
The 23-year-old midfielder had to be withdrawn after 41 minutes of last Saturday's goalless draw at Accrington due to a dead-leg and did not train during the early part of the week.
Fellow midfielder Ryan Burge could also be missing after being recalled by parent-club Doncaster during the week.
However, Wilder insists the youngster has only returned to the Keepmoat for training and may yet line-up against the Spireites.
Another of the club's loanees, winger Simon Hackney, has returned to Colchester early but would not have been fit anyway due to a hamstring injury
Defender Harry Worley completes a two-match suspension after accumulating 10 bookings for the season.