ORCHARD PARK, N.Y. -- Lost in the shuffle as the Buffalo Bills ruffled the feathers of fans by releasing longtime running back Fred Jackson on Monday was some doubt about the status of LeSean McCoy (hamstring) for the regular-season opener Sept. 13 against the Indianapolis Colts.

"Well we certainly expect him to be ready to go, I hope," coach Rex Ryan said Monday. "If not then the next man has to step up. Boobie [Dixon] got a lot of reps out there today. Bryce Brown got a lot of reps today. So we will see. I am not going to put that all on one man. If he is not ready to go, he won’t be in there."

Ryan has used the term "cautiously optimistic" to describe McCoy's availability for the opener. Until Monday, the Bills could have leaned on Jackson as their top option for that game, but now their depth chart at running back is less certain.

If McCoy -- who did rehab work in practices Monday and Tuesday -- can't play in Week 1, then the Bills will most likely turn to Brown or Dixon as their primary ball carriers.

The Bills were in the same spot last November when Jackson and former Bills running back C.J. Spiller were both injured for a Thursday night game to the Miami Dolphins. Dixon and Brown ran a combined 16 times for 49 yards in that game, a 22-9 loss.

If the Bills were limited to Brown and Dixon for their opener, it would be a blow to Ryan's "ground and pound" offense against one of the AFC's best teams last season, the Colts.

Jackson's release also raises the question of which runner would replace McCoy if the star running back suffers another injury this season.

In my view, the favorite for that job would be rookie Karlos Williams. The fifth-round pick might not be available for the opener -- he began rehab work Tuesday at practice after undergoing an undisclosed medical procedure last month -- but down the road could be the better option to replace McCoy than Brown or Dixon.