Dieng is yet to make his competitive debut after injuring his calf in the build up to City's season opener with Port Vale but the Frenchman was able to join in with the rest of his team-mates on Monday.
After missing the win at Peterborough United at the weekend due to a thigh problem, Filipe Morais isn't expected to be risked at Stadium MK either.
A return date at home to Coventry City on Saturday seems a more likely option at this stage for the Portuguese attacker.
Nathan Clarke (calf) is still definitely sidelined, while Matthew Kilgallon is expected to remain in Bradford once again as he continues to work on his fitness levels.
Assistant manager Kenny Black said: "We have probably been a bit unfortunate with injuries over the last couple of weeks. But Tim Dieng trained this (Monday) morning and we are hopeful that he will be back in the squad for tomorrow (vs MK Dons).
"Tuesday night might be a bit too early for Fil (Morais) but we are hoping to have him available for Saturday (vs Coventry City)."