GLENDALE, Ariz. - Arizona Cardinals quarterback Carson Palmer's season may be over due to a torn ACL.

According to Ian Rapoport of NFL Network, the Cardinals believe Palmer suffered the injury while trying to avoid being sacked in the fourth quarter of Sunday's win over the St. Louis Rams by Mark Barron.

He was able to walk off the field, but was taken to the locker room on a cart after that.

Palmer missed three games earlier this season with a damaged nerve in his throwing shoulder.

On Friday, he signed a three-year contract extension worth a reported $50 million with $20.5 million guaranteed.

Arizona trailed 14-10 when Palmer left the game with 11:28 to play.