PITTSFORD, N.Y. -- Days after losing Kiko Alonso to a season-ending knee injury, the Buffalo Bills signed veteran Stevenson Sylvester to bulk up the depth chart at linebacker.

Now the Bills have lost Sylvester to a season-ending knee injury. Though Sylvester wasn't expected to start in Alonso's place, he was considered a strong possibility to make the 53-man roster.

Losing Sylvester could hurt the Bills most on special teams, where Sylvester excelled in four seasons with the Pittsburgh Steelers. In his place, the Bills could lean more on Ty Powell and rookie Randell Johnson for roles on special teams.

Here is a refresher of the Bills' depth chart at linebacker:

Keith Rivers (starter, strong side)

Brandon Spikes (starter, middle)

Nigel Bradham (starter, weak side)

Preston Brown

Randell Johnson

Ty Powell

Jimmy Gaines

Xavius Boyd

The Bills must find a replacement for Bradham in the starting lineup for Week 1. They have used Brown in that spot during practice this week and he's the favorite to take over during Bradham's one-game suspension.

Since Bradham won't count against the roster in Week 1, we predicted that Sylvester would earn the spot as the sixth linebacker. Now, we foresee the Bills keeping only five linebackers on the roster for the opener. Gaines and Boyd, both undrafted free agents, have played sparingly in the preseason and don't seem likely to be on the active roster for Week 1.