Cambridge must do without midfielder Liam O'Neil when hosting Stevenage in Sky Bet League Two on Saturday.
O'Neil was concussed in a nasty clash of heads in Cambridge's goalless draw at Cheltenham on Tuesday.
Cambridge boss Sean Derry admitted O'Neil is still suffering from headaches, so is yet to be cleared for a return to action.
Jabo Ibehre remains a doubt for Cambridge, while Ade Azeez is still sidelined with knee trouble.
Stevenage boss Darren Sarll has doubts over a handful of players, including Tom Pett and Matt Godden.
Forwards Pett and Godden face late fitness tests after they were brought off with injuries during Tuesday's draw with Coventry.
Jack King, who has been plagued with injury problems since the end of last season, will also be assessed ahead of the game after manager Sarll admitted the midfielder is "always fragile".
Experienced defender Ronnie Henry and striker Dan Newton have each had problems in training this week and it is uncertain whether they will be available while winger Ben Kennedy (knee) remains out.
Source: PAR
