PITTSBURGH -- Miami Dolphins starting running back Lamar Miller suffered a concussion in Sunday's game against the Pittsburgh Steelers and will not return.

Miller rushed for 2 yards in the third quarter and was hit hard by Pittsburgh safety Ryan Clark.

Miller immediately left the game after that play and was replaced by Dolphins backup running back Daniel Thomas.

Miller leads the Dolphins in rushing this year with 567 yards on 142 carries and two touchdowns.