(Photo credit: Stephen R. Sylvanie-USA TODAY Sports)

Las Vegas Raiders quarterback Jimmy Garoppolo is in concussion protocol, coach Josh McDaniels confirmed Monday.

Garoppolo was sacked four times but played every snap in Sunday night's 23-18 home loss to the Pittsburgh Steelers.

It is unclear when the injury occurred to Garoppolo, who was never checked during the game and finished with 324 yards, two touchdowns and three interceptions.

Garoppolo, 31, who signed a three-year, $67.5 million deal in the offseason, has thrown for 709 yards, five TDs and six picks in three starts for Las Vegas (1-2).

Veteran Brian Hoyer is the backup quarterback on the depth chart. The 37-year-old journeyman has a 16-24 record across 15 seasons with eight NFL teams.

However, McDaniels would not commit to starting Hoyer if Garoppolo misses time, according to The Athletic.

Rookie Aidan O'Connell, a fourth-round pick from Purdue, played well during the preseason and could push Hoyer for the starting spot if Garoppolo can't go against the host Los Angeles Chargers (1-2) on Sunday.

--Field Level Media