Cardinals linebacker Markus Golden is out for the season after tearing ligaments in his knee.

Markus Golden led the Cardinals in sacks a season ago with 12½, but had yet to notch one this season.

That bothered the linebacker, who repeatedly said he wouldn't "stop hunting." Now he must, after a friendly-fire hit from teammate Budda Baker as both met at the quarterback in overtime tore the anterior cruciate ligament in Golden's right knee Sunday.

Golden was placed on injured reserve Monday. And the Cardinals must find a way to get past losing one of their top pass-rushers, the bookend to teammate Chandler Jones.

"It breaks everyone's heart in there (in the locker room), because they all know how hard he plays," coach Bruce Arians said. "It takes a lot of spirit out of the defense, because he brings it

every play."

Golden's mother Rhonda, who was with her son at the facility Monday, tweeted that her son was OK.

"Thanks everyone for reaching out," the tweet said. "Markus is doing well. Not the report we wanted. However he will be back stronger and better than before."

Kareem Martin will likely take Golden's spot in the lineup, at least initially. Rookie inside linebacker Haason Reddick is a candidate to play outside, especially since the man Reddick had been playing for inside – Deone Bucannon – has returned to the field. Reddick played defensive end in college, and Arians said the Cards could have some special packages for him to rush the passer.

The Cards could also promote from the practice squad. Outside linebackers Bryson Albright and Obum Gwacham each have some NFL experience. With Golden being placed on IR, the Cards currently have one open roster spot.

"We have some decent, different options," Arians said.

Martin was called the most improved Cardinal in training camp by General Manager Steve Keim, and now the Cardinals will need him to show it often.

"Kareem has been playing extremely well," Arians said.

"I'm prepared," Martin said. "It's a next-man-up business, it's a next-man-up team. In football, guys get hurt all the time. I'm praying for Markus, but if my role expands I'm prepared to take that on. Every week I prepare as if I'm the starter, through film and everything, so it won't be any different in terms of that."

Martin had a steep learning curve coming out of college as a defensive end, but said he's finally comfortable in the role of outside linebacker in the Cardinals' system.

"The last couple of years, I've been working my tail off," Martin said. "I've been pushed my Markus and Chandler (Jones) and I had another great camp with these guys pushing me. I'm ready to fill any void that's there."

Golden will be going into the final year of his rookie contract in 2018.

"It's unfortunate," said wide receiver Jaron Brown, who tore his ACL around the same time last season and has returned to play excellent football this season. "I told him to keep his head up. I feel like he's going to take to rehab and come back stronger and better than ever. That's my main message to him."