Carolina Panthers free safety Sherrod Martin landed on injured reserve Monday, one day after tearing the anterior cruciate ligament and medial collateral ligament in his right knee.
Martin wasn't starting, but he was playing more snaps than starter Haruki Nakamura at free safety.
"We've been able to refocus him on the things he needs to improve on, tackling being one of them," coach Ron Rivera said of Martin, according to the Charlotte Observer. "He's really done a nice job. His ability seemed to start to show. He put himself last week in Philadelphia in position to make plays. He got himself in position to make plays (Sunday at Kansas City). That's how he got hurt, trying to make a play."
The injury could affect Martin's marketability as he hits the free agent market following the season.
"I'd definitely love to be here (with the Panthers in 2013)," Martin said, according to the Observer. "But for me to be able to get back on the field, period, I've got to get healthy. So it's just all about one day at a time and just focus on getting back."
In 12 games this season, Martin was credited with 23 tackles, three passes defensed and a forced fumble.
Martin, 28, started every game for the Panthers in 2011 and all but one in 2010. He was selected by Carolina in the second round of the 2009 draft out of Troy.
D.J. Campbell, a seventh-round draft pick in April, saw his first defensive snaps for the Panthers after Martin was injured Sunday.