The unthinkable suddenly seems possible in Indianapolis -- opening the season without Peyton Manning. The four-time league-MVP who has never missed a start in his NFL career is doubtful for Sunday's game at Houston because of lingering soreness in his back following offseason neck surgery. If Manning sits, it would be the first time the NFL's active iron man missed a meaningful game after 227 consecutive starts including the playoffs. Read more: http://espn.go.com/nfl/story/_/id/6932377/peyton-manning-indianapolis-colts-practice-likely-doutbful