Boss Keen prepares for Robins clash.
The U's have played well in recent weeks without due reward and will hope to have an improvement in fortunes from the weekend game onwards.
However, they will be without Alex Gilbey, who saw red in the Essex derby against Southend United and defender Alex Wynter, who continues to recover from concussion.
Also missing is Marvin Sordell, as he looks for fitness as he recovers from an ankle injury.
U's: Parish, Barnes, Brindley, Shorey, Briggs, Kent, Eastman, Vincent-Young, Elokobi, Lapslie, Ambrose, Garvan, Massey, Olufemi, Edwards, Sembie-Ferris, Moncur, Lee, Bonne, Wright, Porter