Bosa was limited by a foot injury again Thursday, putting his availability in question for Sunday's Week 1 matchup against the Kansas City Chiefs.
"It's possible that he might not be with us," said Chargers coach Anthony Lynn, per SoCalNewsGroup. "Foot injuries, they take on all the body weight. That can be tricky."
Bosa has been dealing with the injury to his left foot since he was hurt in practice on Aug. 7. At the time, the ailment was described as "nothing serious."
Bosa was named to the Pro Bowl in 2017 after racking up a team-leading 12.5 sacks while starting all 16 games. Bosa finished with 70 tackles also had four forced fumbles last season.
A first-round pick out of Ohio State (No. 3 overall) in the 2016 NFL Draft, the 6-foot-5, 280-pound Rosa enjoyed a stellar first season with 10.5 sacks in 12 games, earning NFL Defensive Rookie of the Year honors.
Since entering the NFL, Bosa ranks fourth overall with 23 sacks despite missing the first four games of his rookie season with a hamstring injury.
Bosa's potential absence would further deplete Los Angeles' defensive line against the visiting Chiefs in an AFC West matchup.
Chargers defensive tackle Corey Liuget will miss the opener while serving the first of a four-game suspension for violating the league's policy on performance-enhancing substances.