GLENDALE, ARIZ. — Arizona overcame an interception, a missed field goal and the loss of starting quarterback Carson Palmer to injury in the fourth quarter and the Cardinals beat the St. Louis Rams 31-14 for their best start in 66 years.

The Cardinals lead the NFC with a record of 8-1, the best start since the franchise had the same record in 1948 as the Chicago Cardinals.

Arizona has won 15 of its last 18 games under coach Bruce Arians, whose team is 5-0 at home and in complete control of the NFC West. The Rams fell to 3-6.

“It always takes 60 minutes to play this game. That’s why they put it on the clock,'” Cardinals coach Bruce Arians said. “It wasn’t the prettiest 45, but it sure was a nice 15.”

It didn’t look good for the Cardinals early in the fourth quarter.

Palmer was harassed by safety Mark Barron, who grabbed the quarterback’s jersey just enough for Palmer to buckle under his own weight.

He had to be helped off the field and was done for the day. Early reports indicated the Cardinals fear Palmer tore the ACL in his left knee, the same injury that led to reconstructive surgery for Palmer in 2006 with the Cincinnati Bengals.

Rookie kicker Chandler Catanzaro, who had been a perfect 17 of 17 on field-goal attempts, missed a 53-yarder with the Cardinals trailing 14-10.

In stepped backup Drew Stanton, who was forced to start three games earlier in the season when Palmer was out with a nerve issue in his right shoulder. Stanton completed his first two passes, then went deep down the middle and connected with rookie receiver John Brown for a 48-yard touchdown.

It was Brown’s fifth touchdown reception, all of which have come at University of Phoenix Stadium.

“I didn’t see it,” Stanton said, as he was pulled down after throwing the ball. “It’s one of those things that’s a trust factor. You’re putting it up to a spot and ‘Smokey’ went up there and made an unbelievable catch for me.”

After that, the Cardinals’ defense led the way, as cornerback Patrick Peterson returned his second interception in as many possessions 30 yards for a touchdown. Fellow cornerback Antonio Cromartie returned a fumble by quarterback Austin Davis 14 yards for another score.

The Cardinals forced three turnovers in the fourth quarter, a portion of the game they’ve owned all season. They’ve now outscored their opponents 91-34 in the fourth quarter. Only the Chiefs have allowed fewer fourth-quarter points (28).

“Well, I think we learned today that this game is four quarters long. Three doesn’t get it done for you,” Rams coach Jeff Fisher said. “I’m disappointed for (our) guys as hard as they played. Arizona is a good football team. Anytime, regardless of who you’re playing in a close game, you give up three scores like we did in the fourth quarter — however they happen, you don’t have a chance to win.”

With the three forced turnovers, the Cardinals are now tied with the Patriots for the best turnover ratio (plus-12) in the NFL. Of their 19 total takeaways, an NFL-high 12 have come in the fourth quarter.

The Cardinals sacked Davis six times and they entered the game with a total of just eight, tied for the second-fewest in the league.

Davis ended the game 17 of 30 for 216 yards and one touchdown. Before he left the game, Palmer was 25 of 36 for 241 yards with no touchdowns and one interception.

Stanton was 3 of 5 for 85 yards and a touchdown.

What the Cardinals said:

“Unfortunately, we’ve been in that situation before. That’s why you have a confident player like Drew (Stanton) on the roster, to be able to come in and get us a go-ahead score. We’re confident in Drew and whoever is taking snaps.” — Center Lyle Sendlein on what the huddle was like after losing quarterback Carson Palmer to a left knee injury.

What the Rams said:

“It can’t happen. It’s killing our defense. They’re playing their tails off. For is, for me, to have those let downs, it’s really tough. I have to get a lot better and I can’t do that.” — Quarterback Austin Davis on his three fourth-quarter turnovers, two of which were returned for touchdowns.

What we learned about the Cardinals:

1. They can get after the quarterback, after all. Though they entered Sunday’s game with only eight sacks on the season, tied with Oakland for the second-fewest in the league, the Cardinals got to Davis six times, including two by defensive end Calais Campbell. “They didn’t block us,” coach Bruce Arians said. “It’s a simple game.”

2. Rookie kicker Chandler Catanzaro is human after all. After failing to miss on any of his first 17 field goal attempts, the free-agent from Clemson finally missed from 53 yards on Sunday. So obviously, the pressure is now off of him, right? “That’s what (long snapper) Mike Leach was telling me,” Catanzaro said. “It takes a little pressure off. I’m focused on the next-kick mentality. Success or failure on one kick doesn’t mean success or failure on the next kick.”

–QB Carson Palmer may have suffered ACL damage to his left knee, although coach Bruce Arians said nothing would be known for sure until Palmer could get an MRI. Nonetheless, the Cardinals say they are ready to move on without Palmer if they have to. “We have confidence in all of our quarterbacks,” said receiver John Brown. “It’s just like Carson never left. We know Drew; he’ll get the job done.”

–RB Andre Ellington was held to a season-low 23 rushing yards on 18 carries — an average of 1.3 yards per run. “We got our (butt) whipped,” coach Bruce Arians said. “It was simple. We couldn’t block people.”

–CB Patrick Peterson entered the game as the most penalized player in the league with 10 calls going against him and nine penalties accepted. He picked up another one Sunday when he was called for illegal contact. He got the last laugh by making his first two interceptions of the season and returning the second one for a touchdown, but had this to say about the flag: “I guess since I have so many under my belt now, it’s just automatically on 21,” he said. “At the end of the day, like I told you guys early in the week, I can’t let those flags get under my skin.”

What we learned about the Rams:

1. There will be a lot of talk about how the Rams may have lost their poise in the fourth quarter on Sunday, that this is a young team that still isn’t sure how to close out games without some type of trickery or luck. Coach Jeff Fisher thinks that’s nonsense and he’s right. “We didn’t lose poise. We just gave up some plays and plays happen,” he said. “They made the plays, we didn’t. I believe in these guys and I’m not buying into all that business about us not being able to complete a game. The record reflects it and statistics reflect it, but we’re going to keep doing the things we’re doing because I believe in them.”

2. Quarterback Austin Davis still is trying to acquire his touch on throws beyond the routine dinks and dunks underneath. He is still growing into the position and knows he’s not anywhere close to perfect. “I think the thing I’m learning really quick is you can play well for three and a half quarters, but you have to play four,” he said. “You can’t have a single letdown. Right now I am having those and it’s costing our football team.”

–S Lamarcus Joyner injured his groin in the second quarter. “We moved E.J. (Gaines) into nickel, then we played Mark (Barron),” coach Jeff Fisher said. “We played a little bit more than we anticipated with Mark in the package. Now Mark’s packages will continue to increase. You can see what he does. He’s a good football player and he made some big plays for us.”

–LB Alec Ogletree had an interception, a forced fumble, three passes defensed and seven tackles. “I’ve been practicing hard all week,” he said. “… It definitely didn’t come out the way we wanted it to come out. We just have to get ready for next week.”

–TE Jared Cook has had his big moments against the Cardinals in the past, including seven catches for 141 yards and two touchdowns in a game last season. On Sunday, he stretched the field to haul in 59-yard touchdown pass from Austin Davis that game the Rams a 14-10 lead.