He had been listed as probable most of this week after returning last weekend following in-season knee surgery Oct. 9, but team doctors found swelling in the knee Saturday.
Team officials now say Brown will be re-evaluated before the Colts (4-3) turn in their list of inactive players 90 minutes before kickoff. If Brown does not play, rookie Vick Ballard likely would see the bulk of the action. Ballard has started the Colts' last three games.
The Colts host the Dolphins (4-3) in a matchup between teams that have surprised everyone by starting rookie quarterbacks and managing to spur talk of playoff hopes among their fans this season. Game time is 1 p.m.
Copyright 2012 The Associated Press