Update (Monday, 12:00 p.m. ET): According to multiple reports, tests revealed that Mathieu tore both his ACL and LCL Sunday. The injuries will end his promising rookie season.
Tyrann Mathieu has been everything the Cardinals hoped for and much, much more since they rolled the dice on him in the 2013 draft. Now, they may have to continue their surprising playoff push without him.
Mathieu injured his knee on a kick return in Sunday's win over the Rams, and Arizona coach Bruce Arians said that it appears Mathieu tore his ACL. An MRI Monday could confirm that injury, which obviously would end Mathieu's exceptional rookie season -- and may put him at risk of missing part of the 2014 campaign, as well.
The injury occurred in the third quarter, as Mathieu attempted to return a free kick following a safety. He was tackled by St. Louis' Isaiah Pead, with his leg appearing to bend awkwardly in the process. Mathieu tried to jog to the sideline after getting to his feet, only to collapse in front of the Arizona bench as his leg buckled.
Mathieu had played so well through Arizona's first 12 games that he was considered a contender for the Defensive Rookie of the Year award. He entered Sunday with two interceptions and 67 tackles. The one-time LSU star also graded out as Pro Football Focus' No. 2 cornerback in all of football, behind only Darrelle Revis.
Losing Mathieu now would be a crushing blow to the Cardinals, who still sit just a game back in the wild-card race. And for Mathieu, it would be quite the anti-climactic finish to a 2013 season that saw the once-troubled defensive back work his way onto the straight and narrow.
The Cardinals play at Tennessee next week, before finishing the year with a back-to-back against the NFC West's top two teams (at Seattle, vs. San Francisco). With or without Mathieu, they'll need to find a way to win at least two of those final three games -- including the finale against the 49ers
-- if they want to extend this season into a playoff berth.