COSTA MESA, Calif. -- Los Angeles Chargers defensive end Joey Bosa did not practice for a second straight day and has been ruled out of Sunday's season opener against the Kansas City Chiefs due to a left foot injury.
According to the Chargers, Bosa's left foot injury from a month ago has healed and he suffered a new injury to the same foot during practice Wednesday.
Chargers head coach Anthony Lynn said that Bosa is week to week, and that his foot is not broken. Bosa was on the field, going through individual drills, and felt something wasn't right in his left foot, according to Lynn.
Bosa declined to comment on the injury when approached by reporters in the locker room after practice Friday.
"It's very frustrating," Lynn said. "He's been waiting for a while to get back on the field, and he's doing everything he can. He just wants to be out there with his teammates. He's pretty frustrated right now."
Bosa suffered the initial injury, described by Lynn as a sore foot, on Aug. 7 during 11-on-11 team drills in practice. Afterward, Bosa hobbled off the field on his own and spent the rest of practice receiving treatment from the team's training staff.
Bosa did not participate in any preseason games. However, the Chargers considered his injury minor and the expectation was he would be ready for the beginning of the regular season.
That all changed on Thursday, when Lynn said that Bosa might not play on Sunday after being a limited participant in practice on Wednesday.
"Foot injuries, they take on all the body weight," Lynn said this week. "That can be tricky, something you don't want to rush. You want to make sure that's right before a player comes back."
With Bosa out, second-year pro Isaac Rochell likely get the start at defensive end.
Rochell started all four of the preseason games for the Chargers at defensive end in place of Bosa, finishing with nine combined tackles and two sacks. "The preseason starts definitely gave me the confidence of who I am as a player, and kind of let me develop myself as 'starter' during that time," Rochell said.
The Chargers also were looking to add depth at defensive end this week. ESPN Insider Field Yates reports that according to a source, the Chargers were one of four teams to put a waiver claim on Anthony Zettel -- released by Detroit Lions -- along with the Cleveland Browns, Green Bay Packers and Minnesota Vikings. Cleveland had top waiver wire priority.
The No. 3 overall selection of the 2016 draft, Bosa led the Chargers in sacks last season with 12.5, and he is one-half of the Chargers' talented pass-rush tandem that includes Melvin Ingram, who finished with 10.5 sacks last year.
Bosa played a full 16-game season for the first time in his NFL career in 2017, earning a trip to the Pro Bowl. Bosa missed the first four games of his rookie season with a hamstring issue after sitting out of training camp because of a contract dispute.