Keegan suffered a dead leg during the home defeat to Walsall on Saturday and had to come off after 65 minutes. He will continue to be monitored ahead of Tuesday night's game.
Fellow midfielder David Syers is also a doubt. Syers missed out against the Saddlers after an ankle injury forced him off in the defeat at Bury on February 2.
Another midfielder, Martin Woods, was an unused substitute at the weekend having been out since November with a thigh injury and perhaps he will take the next step by making a return to action against the Dons.
The game at the Keepmoat Stadium will be the first between the two clubs this season.
The Dons were originally due to travel to South Yorkshire in December but freezing temperatures saw the game postponed.
The fixture at stadium:mk has also had to be re-arranged due to the Dons' ongoing involvement in the FA Cup.