Red card rules out skipper.
The U's face Sheffield United on Tuesday evening, without captain Magnus Okuonghae.
Suspension keeps out the U's skipper, following his dismissal at Leyton Orient at the weekend.
Frankie Kent came on to partner Tom Eastman against the O's and the youngster is expected to keep his place for the Blades' visit to north Essex.
On the injury front, the U's will still be without Jabo Ibehre as he continues his recovery from a knee injury.
U's: Walker, Lewington, Clohessy, Eastman, Gordon, Kent, Wright(David), Gilbey, Eastmond, Bean, Moncur, Szmodics, Sears, Vose, Massey, Watt, Bonne, Holman