COSTA MESA, Calif. >> Los Angeles Chargers rookie outside linebacker Tuli Tuipulotu stepped up when Joey Bosa was limited in the first month of the season because of hamstring and toe injuries.

With Bosa set to miss more time because of a sprained foot, Tuipulotu is ready to use that experience and help the Chargers get back on track.

“Those games, I had to gain confidence in myself because it was my first time starting in the league,” Tuipulotu said. “I needed to make sure I played hard and did my job so I could gain that confidence and be comfortable for times like this.”

Tuipulotu went from playing 33% of the defensive snaps in his debut against Miami to being on the field for at least 77% of plays in each of the next three weeks against Tennessee, Minnesota and Las Vegas, reaching a high of 86% in the win against the Raiders.

He had 15 tackles, five quarterback hits, three tackles for loss and two sacks in that three-game span, showing why the Chargers (4-6) drafted him 54th overall in the second round.

Defensive tackle Sebastian Joseph-Day said Tuipulotu’s mentality and work ethic allowed him to make an effective transition from college, where he was first in the FBS in sacks and second in tackles for loss as a junior at Southern California.

“First and foremost, I feel like Tuli is very mature for his age and for the opportunity he has,” Joseph-Day said. “He does a really good job even in practice. He’s always the first one out there, getting extra reps, always knowing what he has to do.”

“His growth has been amazing. It isn’t surprising because of the way he goes about his business each and every day.”

Coach Brandon Staley praised the consistency of Tuipulotu, who has 31 tackles, eight tackles for loss and four sacks.

“There have not been any peaks and valleys. It’s just been he keeps going this way,” Staley said, raising his arm up at an angle to emphasize the trajectory.

Tuipulotu’s approach is similar to that of Bosa, Joseph-Day said. Not surprisingly, Tuipulotu has been leaning on Bosa to help his transition to the NFL.

With Bosa placed on injured reserve Wednesday, ruling him out of at least the next four games, Tuipulotu made it a point to request the veteran pass rusher will be available even as he focuses on rehabilitating the injury sustained in the 23-20 loss at Green Bay on Sunday.

“I got to talk to Joey the other day, and I just asked him to still be here just ‘cause I need him,” Tuipulotu said.

Tuipulotu has seemingly endeared himself to Bosa, who copied his sack celebration and put up a “T” against the New York Jets in a Week 9 win.

Safety Derwin James Jr. understands why Bosa embraced Tuipulotu.

“He doesn’t say too many words in the building, but he has a lot of swag energy when he plays,” James said, describing Tuipulotu’s personality. “He lets his play do the talking. I like a guy like that, for sure.”

The Chargers expect Tuipulotu will do his part to help overcome the absence of Bosa, who has 6 1/2 sacks and six tackles for loss in nine games.

“Obviously, losing Joey is a huge loss,” Joseph-Day said. “Joey, he’s a phenomenal player, but Tuli has done such a great job for us in the past and I think he’s gonna do a great job moving forward.”

NOTES: WR Keenan Allen (shoulder) was limited in practice. … Putting Bosa on IR allowed the Chargers to call up OLB Andrew Farmer II off their practice squad. They signed FB Zander Horvath to the practice squad.