TEMPE, Ariz. -- Tyrann Mathieu is about to begin a long and tedious road to recovery.
The Arizona Cardinals rookie free safety will have surgery Friday to repair his left ACL and LCL, which he injured in the third quarter of Arizona's 30-10 win over St. Louis on Sunday. He plans on staying in Arizona for his rehabilitation, instead of going back to Florida or rehabbing at Louisiana State University.
There isn't an official timeline for his return, although rehab from a multi-ligament surgery has been estimated to take about nine months. Earlier this week, coach Bruce Arians said he doesn't expect Mathieu to be ready for training camp.
"Yeah, I heard that," Mathieu said. "Coach is just being generous. He doesn't want to rush me back. Hopefully everything goes well and goes fast."
The knee is still sore but isn't too painful, Mathieu said. He expects that to change after Friday's surgery. On Monday, he'll visit with team doctors and trainers to lay out a plan for his recovery, but Mathieu's already experienced the monotony of what's in store for the foreseeable future.
This week, he's come in early to begin preparing for surgery, sat in on the defensive back meetings and then got treatment. It's already become routine for the third-round draft pick.
"I haven't really been depressed but not having football, you don't know what to do with your time," he said. "Just sitting on your behind all day, it's kind of boring. That's the only frustrating thing I've come across in the last couple days."
Mathieu said he knew something was wrong when a Rams player jumped on his left knee during a return from a free kick. But he didn't know how serious the injury was until he tried jogging off the field and the knee buckled near the Cardinals' sideline.
That's when Mathieu got scared because, for the first time in his career, he had suffered a major injury. "From that point on, I just had to listen to others and other people who had been through it," Mathieu said. "So, I didn't know what to think because I hadn't been through it."
Mathieu isn't sure where he'll watch Sunday's Cardinals-Titans game. He doesn't have an elaborate entertainment system ready to go. He might just pop some popcorn and sink into his couch with his cell phone at the ready. He'll watch every second of the game and "probably text them at halftime."
This won't be the first time Mathieu will be watching his team play from afar.
He missed the 2012 season at LSU after being dismissed that August for failing drug tests. He watched from home and in the stands at Tiger Stadium, so he knows what to expect.
"I kinda prepared myself last year not playing at LSU, being on campus and not being able to be a part of the team," Mathieu said. "I think I'm somewhat prepared in that aspect. I regret what I've been through but some of those things are starting to help me today."
Among the frontrunners for Defensive Rookie of the Year, Mathieu hasn't reflected on what he's accomplished in 2013.
Besides his 63 tackles, two interceptions, one sack and one forced fumble, Mathieu believes he's raised the standard for rookie defensive backs on the Cardinals. But the best, he said, was yet to come.
That, alone, will serve as Mathieu's motivation to get back on the field -- whenever that is.
"Hopefully," he said, "I can come back like A.P. [Adrian Peterson]"