Ben Margot/Associated Press

Arizona Cardinals safety Tyrann Mathieu left the field in the fourth quarter of a Week 15 game against the Philadelphia Eagles with what was later determined to be a torn ACL in his right knee that required surgery.

Continue for updates.

Mathieu Undergoes Surgery

Tuesday, Jan. 12

Head coach Bruce Arians said Mathieu's surgery went well and that he's in "great spirits," per Omar Ruiz of NFL Network.

Mathieu Placed on IR

Tuesday, Dec. 22

Darren Urban of AZCardinals.com reported the team signed safety Chris Clemons to take Mathieu's place on the roster.

Mathieu's Season Over After Testing

Monday, Dec. 21

Head coach Bruce Arians told reporters an MRI revealed Mathieu tore his right ACL. Arians added Mathieu will have surgery "in the next couple of weeks." Adam Green of Arizona Sports 98.7 FM noted Arians was "visibly shaken" by the diagnosis.

James Palmer of NFL Network reacted to the news, calling it a "huge blow," adding Cardinals players told him Mathieu's versatility is "what makes this defense what it is."

Mathieu X-Ray Results Revealed

Sunday, Dec. 20

After the Cardinals' 40-17 win, NBC's Bob Costas reported X-rays on Mathieu's knee were negative, per Kyle Smith of the Score.

Conor Orr of NFL.com noted trainers had to help Mathieu off the field.

Mathieu Has Developed Into Defensive Star Despite Troubles at LSU

Mathieu tore his left ACL and LCL in December 2013 but still managed to return and play 13 games the next season, and a fractured left thumb is what held him out for two of the three contests he missed in 2014. Otherwise, he has had a rather clean bill of health through three NFL seasons.

The former LSU standout, who struggled with marijuana use prior to being drafted, has proven to be a steal for Arizona as a 2013 third-round pick. Capable of playing nickel cornerback in addition to safety, Mathieu has uncanny instincts in coverage and a nose for the football that can't be emulated.

Rashad Johnson and Tony Jefferson are similarly versatile defensive backs and can line up in multiple spots in the Cardinals' multifaceted defense. One of them figures to fill in at Mathieu's starting free safety spot as Arizona continues its run toward the Super Bowl.