Rams blow 4th-quarter lead, lose to Arizona 31-14

GLENDALE, Ariz. (AP) — The St. Louis Rams were beating the team with the best record in the NFL. They were facing a backup quarterback, and it was the fourth quarter.

Then everything fell apart for the Rams, and the Arizona Cardinals erupted for a 31-14 victory.

Patrick Peterson intercepted Austin Davis twice on Sunday, returning the second 30 yards for a touchdown. Then Davis fumbled the ball away after a crushing hit and Antonio Cromartie returned it 14 yards for a score.

"It can't happen," Davis said. "It's killing our defense."

Arizona (8-1) scored three touchdowns in a span of 3 minutes, 48 seconds after Cardinals quarterback Carson Palmer went down with a knee injury.

"We don't know anything about Carson's injury or the length, whatever it is yet," Arizona coach Bruce Arians said. "He will be evaluated and get an MRI and everything and we will know something by tomorrow and hopefully by Tuesday."

On the first possession after Palmer was hurt, rookie John Brown's diving grab of backup Drew Stanton's 48-yard touchdown pass put the Cardinals up 17-14 with 7:40 to play.

"That is what I am here for," Brown said. "That is why coach Bruce Arians brought me in for, to make big plays. They say big-time players step up in big time games so I try to do the best I can when it is my time. "

Palmer was taken to the locker room on a cart after being helped off the field.

It was the same left knee that he injured Jan. 8, 2006, in a playoff game against Pittsburgh, when he tore his ACL and MCL on his first pass of the game.

"I think there's a question mark there because nobody knows what his status is," Stanton said. "It's difficult because he is the leader of this team. ... We'll just continue to weather the storm, whatever it is."

St. Louis (3-6) was shut out in the second half.

The Rams pointed to a crucial penalty after a 41-yard pass to Jared Cook had put the ball on the Arizona 4-yard line late in the third quarter. But Lance Kendricks was called for a blindside block, a 15-yard penalty that pushed St. Louis back to the Cardinals' 45. Calais Campbell's second sack of the game eventually pushed the Rams out of field-goal range.

"I thought it was a clean hit," Kendricks said.

Rams coach Jeff Fisher also mentioned Palmer's tackle of Alec Ogeltree after a third-quarter interception. Had the tackle not been made, Fisher said, Ogeltree might have scored.

Cook got behind rookie Deone Bucannon for a 59-yard touchdown pass with 1:50 left to give St. Louis a 14-10 halftime lead. The Rams held that lead until midway through the fourth quarter.

"The thing that I'm learning really quick is you can play really well for three and a half quarters," Davis said, "but you've got to play four. You can't have a single letdown and right now I'm having those and it's costing our football team."

At 8-1, the Cardinals have their best record after nine games since going 11-1 as the Chicago Cardinals in 1948.

Palmer was playing some of the best football of his career and, on Friday, signed a three-year contract extension worth a reported $50 million with $20.5 million guaranteed.

On third at the Rams 28, Palmer dropped back to pass, then tried to avoid blitzing safety Mark Barron. The quarterback's leg gave way and Barron touched Palmer for a sack.

Stanton went 2-1 as a starter earlier this season when Palmer was out with a damaged nerve in his throwing shoulder.

"Everyone has confidence in Drew," Arians said. "Nothing drops off."

On Peterson's second interception, the ball bounced off of his hands and those of the Rams' Kenny Britt. Peterson caught it and raced to the end zone for the score. On St. Louis' next possession, Kareem Martin hit Davis and the ball came free as he tried to pass. Cromartie picked it up and ran in for the score to put Arizona up 31-14 with 3:58 to play.

Arizona has outscored opponents in the fourth quarter 91-34.

"I think we learned today that this game is four quarters long," Fisher said. "Three doesn't get it done for you."

NOTES: Arizona had six sacks after getting eight in its first eight games. ... The Cardinals have 14 interceptions and a plus-12 turnover ratio. ... St. Louis lost safety Lamarcus Joyner in the first half to a groin injury. ... Fitzgerald moved ahead of Keenan McCardell on the career receptions list and passed Michael Irvin into 24th in career yards receiving.

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