GLENDALE, Ariz. -- Carson Palmer didn't throw a pass in practice all last week, then completed practically every one he tried Sunday.
So much for that sore right elbow.
It was the second-highest completion percentage (84.4) in franchise history. Only Kurt Warner's NFL record of 92.3 percent (24 of 26) against Jacksonville in 2009 was better.
Palmer said he had no idea what his statistics were, just that things were working at a nice clip.
"When the plays were coming in I knew exactly where to go with the ball," he said.
Palmer hurt his throwing elbow in last week's loss at Philadelphia. From Monday on, trainer Tom Reed decided there would be no passing in practice.
"I didn't throw one ball, and I was definitely worried about that," Palmer said, "but that was the plan."
It worked to near perfection.
Palmer threw for 269 yards and a touchdown with no interceptions as the Cardinals (8-5) won for the fifth time in six games. He was sacked once.
"I can't say enough about where he is right now," Arizona coach Bruce Arians said. "The level he's playing is extremely high."
Tavon Austin's 56-yard run set up the only touchdown for the Rams (5-8), a 1-yard run by Zac Stacy. Austin injured his left ankle on the play and didn't return. The loss mathematically eliminated the Rams from postseason contention.
The Cardinals lost rookie safety Tyrann Mathieu in the third quarter. Arians said it "appears to be an ACL" injury to his left knee.
Arizona had not beaten an NFC West opponent since downing Seattle in the 2012 opener. The Cardinals lost three in a row this season, including 27-24 at St. Louis in the opener. Arians hammered that home last week.
"I can't use the words he used," Dansby said. "My mom would get at me if I do that, but he let it be known that we were at the bottom of the totem pole and we've got to climb our way out."
Fitzgerald's 12 catches went for 96 yards, including a 7-yarder for a touchdown. It was his most receptions since he matched his career high with 13 against Seattle on Oct. 18, 2009.
Dansby had his second touchdown return of an interception in three games. He returned one 22 yards in Arizona's 40-11 rout of Indianapolis.
Mathieu, the "Honey Badger" having a terrific rookie season, was hurt after returning the free kick that followed the safety in the third quarter. He jogged toward the Arizona bench but his knee buckled and he collapsed, then he was carted off the field.
The Arizona safety came after a Cardinals punt was downed at the Rams 1. On third down from the 5, Clemens retreated to the end zone and was hit by Abraham, who had three sacks to give him 11 this season.
Other than Austin's big run, St. Louis managed just 44 yards on the ground in 18 attempts. Rams coach Jeff Fisher said he was well aware how strong Arizona's defensive front was.
"I thought we would do a better job than we did, but we couldn't run the football today," he said.
In the first half, Palmer completed 16 of 17 for 169 yards and a touchdown. He would have had another TD had Jim Dray not fumbled at the half-yard line. Palmer completed his first 10 passes.
On St. Louis' second play from scrimmage in the third period, Calais Campbell pressured Clemens. Dansby stepped in front of intended receiver Jared Cook, picked off the pass and ran untouched 23 yards to make it 21-3.
Abraham moved past Lawrence Taylor and Leslie O'Neal into ninth on the NFL career sacks list with 133. ... Dansby has four interception returns for scores for the Cardinals in two stints with the team. Only Aeneas Williams (six) and Larry Wilson (five) have more in franchise history. ... Arizona has outscored its last two opponents at home 70-21 and is 6-1 at home. ... The Rams were penalized 11 times for 90 yards. ... With his 10th TD catch of the season, Fitzgerald became the ninth player with double-digit touchdown receptions in five seasons.