The Pittsburgh Steelers put linebacker Vince Williams on the reserve/COVID-19 list Thursday, knocking their leading tackler out of this week’s game against the Buffalo Bills.

Per NFL protocols, Williams needs to be on the list for at least five days, even if he hasn’t tested positive for COVID-19. It’s Williams’ second stint on COVID reserve; he was deemed a high-risk close contact of tight end Vance McDonald earlier this season.

It’s another blow to the Steelers’ linebacking corps, already without Devin Bush (out for season) and Robert Spillane (knee), who’s expected to miss time. Further, outside linebacker Bud Dupree tore his ACL last week and was put on injured reserve.

Williams leads the Steelers in tackles with 63 to go with three sacks. He ranks fourth in the NFL in tackles for loss (14) and has two fumble recoveries in 12 games, all starts.

The Steelers (11-1) visit Buffalo on Sunday to take on the AFC East-leading Bills (9-3). The Steelers are coming off their first defeat of the season, a 23-17 loss to Washington (5-7).