COSTA MESA, Calif. (AP) -- Los Angeles Chargers linebacker Denzel Perryman is likely to be out for at least two months after injuring his ankle in the preseason opener.

Perryman had surgery on a torn ligament in his left ankle Tuesday, coach Anthony Lynn said. The Chargers' starting middle linebacker will miss at least several regular-season games, but Lynn was pleased to know Perryman will return this season.

"It's a blow," Lynn said. "It's a position (where) we're looking for depth, and these young guys will have to step up and play a little bit."

Those young guys include Korey Toomer and Nick Dzubnar, two backups likely to be thrust into important roles in the Chargers' new 4-3 defensive scheme.

The Chargers were dogged by major injury woes in their last two seasons in San Diego, and their new era got off to a dishearteningly familiar start: Perryman got hurt on a non-contact play during the first defensive series of their first game since relocation, leaving the StubHub Center field on a cart.

Perryman started 11 games for the Chargers last year, making 80 tackles and two sacks in his second pro season. The second-round draft pick out of the University of Miami had assumed a prominent role during Los Angeles' offseason work.

"Denzel was looking to step up as a leader, and he did," Lynn said. "He was one of our leaders on the team, and he still will be. He'll be around. He'll be in the meetings. He'll be at practice. He just won't be on the field."

Perryman was making a strong transition after the Chargers changed their defense during the offseason to a 4-3 front under new coordinator Gus Bradley, the former Jacksonville head coach and Seattle defensive coordinator.

Toomer spent his first two NFL seasons in Bradley's defensive scheme with the Seahawks. Toomer started eight games for the Chargers last season, and he has been ahead of the game since Bradley's arrival.

"It helped a lot," Toomer said. "Being in that defense early on in my career, it just shows me little stuff that I need to work on, as far as not having to worry about the defense as a whole. I can worry about technique work and the fundamentals."

Dzubnar also feels more comfortable in a 4-3 scheme similar to his college experience at Cal Poly. The undrafted product of nearby Mission Viejo High School is among the Chargers' most important special teams contributors, but he is attempting to play his way into a significant role on the defense after tearing a knee ligament early last season.

"I knew coming into this year, I was just like an undrafted rookie again," said Dzubnar, who celebrated his 26th birthday Tuesday. "I had to make a name for myself again, because these coaches don't know anything about me. They weren't here last year. So I knew I was going to treat this year like my undrafted rookie year and just do what I can."

The Chargers also signed linebacker Kyle Coleman and waived/injured rookie linebacker Mike Moore, who had been listed as the third-string middle linebacker on the opening depth chart. Coleman went to training camp with Seattle in each of the past two offseasons, getting waived most recently by the Seahawks one week ago.

Los Angeles remained without first-round pick Mike Williams, who is still three weeks away from practicing after injuring his back in the offseason. Lynn remains encouraged by Williams' progress, but the seventh overall pick last spring is still not ready to contribute.