As if the Buffalo Bills haven't dealt with enough injuries on offense, there's now one more to add to the list.

Rookie running back Karlos Williams suffered a concussion in Sunday's Week 4 loss to the New York Giants and is currently going through concussion protocol. Williams is the primary backup to LeSean McCoy, who's dealing with a hamstring injury himself.

"[Williams] told our trainers several hours after the game that he wasn't feeling well and our medical staff took a look at him," general manager Doug Whaley told WGR 550, via ESPN. "They put him through further evaluations late yesterday afternoon and it was determined that he'll have a concussion. So we'll see how he proceeds throughout the week."

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McCoy has already said that he won't return until he's 100-percent healthy, and that may not be for another three to four weeks. It's clear the Bills missed him and Sammy Watkins on Sunday as they were able to put up just 10 points on offense.

Williams' status for Week 5 is now uncertain, with Boobie Dixon and Cierre Wood in line to receiver more touches if he's unable to go. Through four games, Williams is the only player in the NFL to score a touchdown in each week, which proves his value to the team.

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