Cardinals fear Carson Palmer suffered torn ACL in left knee

Doctors feared that Arizona Cardinals quarterback Carson Palmer suffered a torn anterior cruciate ligament in his left knee during Sunday’s victory over the St. Louis Rams, according to a person familiar with the situation.

Tests must confirm the severity of the injury, according to that person, who spoke on the condition of anonymity because the Cardinals had not announced details. If Palmer indeed suffered a torn ACL, his season would be over.

Cardinals Coach Bruce Arians did not divulge details of Palmer’s injury during his postgame news conference. Arians said that Palmer would undergo testing and the Cardinals hoped to know more by Tuesday.

Palmer, 34, signed a three-year, approximately $50 million contract extension with the Cardinals that was announced Friday. The deal runs through the 2017 season and contains about $20.5 million in guaranteed money.

Palmer also suffered a torn ACL in his left knee in a playoff game for the Cincinnati Bengals at the end of the 2005 season.

Backup quarterback Drew Stanton took over Sunday for Palmer. He also made three starts earlier this season while Palmer was dealing with an ailing right shoulder related to a nerve issue. The Cardinals went 2-1 in those games. They improved their NFL-best record to 8-1 with Sunday’s 31-14 triumph over the Rams.