COSTA MESA, Calif. — Chargers quarterback Philip Rivers is listed as questionable for Los Angeles' game against Buffalo on Sunday due to a concussion.

Rivers is still progressing through the NFL's concussion protocol after he reported symptoms of a head injury on Monday.

Rivers participated fully in practice with the Chargers on Friday for the second straight day, but he must be cleared by a neurologist before Los Angeles can allow him to play again. Chargers coach Anthony Lynn says he is optimistic Rivers will play.

Rivers has started 194 consecutive games for the Chargers since taking over for the 2006 season opener. His 185 straight regular-season starts are the second-longest active streak for quarterbacks behind Eli Manning's 208.

Kellen Clemens is Rivers' backup.

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