Captain Jake Wright (groin) and Jon Meades (ankle), who has yet to make his Oxford debut, are still sidelined.
Teenager Callum O'Dowda could start after impressing off the bench in Saturday's 2-0 home defeat to Southend. James Constable is also in contention after making successive substitute appearances on his comeback from a foot injury.
Oxford, who were given a bye to the second round, reached the southern area semi-finals last season before falling to Southend.
- Sports & Recreation
- James Constable