Los Angeles Chargers wide receiver Keenan Allen has been added to the team's injury list due to an illness and is questionable to play during the squad's game against the Las Vegas Raiders, Adam Schefter of ESPN is reporting.

Although the exact nature of the illness has yet to be reported, it is notable that Allen was not placed on the COVID-19/reserve list, making it unlikely that the wideout had contracted coronavirus or was in close contact with it—an occurrence that might require him to miss games beyond this week.

This appears to have been the case with cornerback Brandon Facyson, who was moved to the reserve list Saturday afternoon. Further, Allen was dealing with a back injury earlier in the season—not an illness.

A mainstay of the Chargers offense since he was selected in the third round of the 2013 NFL Draft, the former Cal product has accrued 53 catches on the year, to go along with three receiving touchdowns and over 500 yards. A favorite target of the rapidly ascending quarterback Justin Herbert, the seventh-year veteran has been targeted more than any single receiver in the league, besides Stefon Diggs, Amari Cooper, and Allen Robinson—despite playing a game less than all three.

Without their star wideout, the Chargers will likely move Mike Williams into the No. 1 receiving spot, and transition KJ Hill Jr into the starting group against Las Vegas. Only 2-5 on the year, Los Angeles enters Sunday's game in desperate need of a win as they look to climb out of the cellar of the AFC West division, trailing the Raiders by only two games, despite their early season struggles.