The Raiders signed third-year linebacker Bruce Davis Jr. on Tuesday for insurance in case linebackers Thomas Howard and Quentin Groves aren't able to rebound quickly from injuries.

Veteran defensive tackle Jay Alford was released to make room for Davis on the 53-man roster. The Raiders also waived cornerback Joey Thomas from the injured-reserve list.

The Raiders did not announce any of the transactions. All three were confirmed by two league sources.

Davis did not return a phone call.

Davis was signed from the 49ers practice squad. Teams are permitted to sign a player from another team's practice squad provided they place him on their 53-man, active roster.

Groves and Howard suffered hamstring and knee injuries, respectively, against the Houston Texans on Sunday and were unable to finish the game.

Besides Howard, the Raiders' other reserves linebackers are Ricky Brown, Trevor Scott, Sam Williams and Travis Goethel. Brown is out with a hamstring injury, Scott has played defensive end the first four games, and Williams' primary role is that of a core special teams player. Goethel has missed the first four games with a back injury.

Davis is the son of former Raiders offensive tackle Bruce Davis, who played for the team from 1979-87.