The Las Vegas Raiders placed quarterback Marcus Mariota on injured reserve Monday, the team announced.
Mariota missed multiple practice sessions last week as he's been battling a pectoral strain, according to NFL Network's Ian Rapoport. The signal-caller will now miss at least the first three weeks of the season under the NFL's COVID-19 roster guidelines.
The 26-year-old, who's set to back up Derek Carr this season, inked a two-year deal with the Raiders last March after spending the previous five campaigns with the Tennessee Titans.
The 2015 second overall pick has posted a 29-32 regular-season record as a starter in the NFL.
Las Vegas, which opens its season Sept. 13 on the road against the Carolina Panthers, is expected to have Nathan Peterman as its No. 2 signal-caller until Mariota returns.
The Raiders also signed quarterback DeShone Kizer to their practice squad Monday.