The Buffalo Bills’ backfield is banged up at the moment.

LeSean McCoy has battled a hamstring ailment all season, and now backup Karlos Williams has his own injury issue. Bills general manager Doug Whaley told WGR-AM in Buffalo on Tuesday that Williams suffered a concussion in the team’s Sunday loss to the New York Giants.

“We’re going to see how he proceeds throughout the week,” Whaley told WGR, per the Bills’ team website. “With the concussion, you just don’t know how they’re going to respond.”

The rookie running back will enter the NFL’s concussion protocol, and his status for the Bills’ Week 5 matchup with the Tennessee Titans is up in the air. Williams was a standout in the Bills’ Week 3 win over the Miami Dolphins, rushing for 110 yards on just nine carries. He was bottled up for the most part against the Giants with just 40 yards on 18 carries, but he did catch three passes for 30 yards, including a touchdown.

NFL Media’s Ian Rapoport reported the Bills are working out “a handful” of running backs Tuesday, including free-agent veteran Trent Richardson.

Thumbnail photo via Timothy T. Ludwig-USA TODAY Sports Images