GLENDALE, Ariz. -- Although Arizona Cardinals quarterback Carson Palmer was listed as questionable with a sore right passing elbow, there was no question in his mind that he would play Sunday against the St. Louis Rams.
The Cardinals, trying to stay in the hunt for an NFC wild-card berth, needed Palmer, and he came through in a big way.
Palmer completed 27 of 32 passes for 265 yards and a touchdown, finding star receiver Larry Fitzgerald early and often, and the Cardinals cruised to a 30-10 victory over the Rams at University of Phoenix Stadium.
"I think the rest did him well," Cardinals coach Bruce Arians said of Palmer, who practiced on a limited basis last week but did not throw a single pass in workouts. "I think he set the second-highest completion percentage in club history. That was exactly the performance that we needed. He protected the ball extremely well and I can't say enough about the way he is right now and how the level he is playing at is extremely high."
It was the fifth win in the past six games for the Cardinals (8-5), and it keeps their playoff hopes alive, although they are still on the outside looking in.
If they do reach the postseason, they may have to do it without rookie safety Tyrann Mathieu, who suffered a left knee injury in the third quarter and had to be carted off the field.
Mathieu's status was not immediately known, but it did not look good and Arians said there are initial concerns that Mathieu may have suffered a torn ACL. He was tackled awkwardly after fielding a short punt, but seemed to be OK. Then he collapsed while jogging off the field.
"When a guy goes down and gets carted off the field, you've just got to keep your fingers crossed," Cardinals safety Rashad Johnson said. "You're hoping for the best and just wishing that whatever it is, it's a speedy recovery and we get him back on the field."
The Rams (5-8) have now dropped two straight since beating the Indianapolis Colts and Chicago Bears in blowout victories. They were held to 257 net yards against the Cardinals and 56 yards came on a reverse by rookie wide receiver Tavon Austin, who left the game in the third quarter with an ankle injury.
"I thought we'd do a better job than we did, but we couldn't run the football today and that's disappointing," Rams coach Jeff Fisher said. "Stats certainly are misleading with Tavon's reverse, but really that's the difference in the ballgame. They did an outstanding job against our run game. We turned the ball over, we had too many penalties and we got beat."
Fitzgerald looked like the perennial Pro Bowl receiver of old, catching a season-high 12 passes for 96 yards and a touchdown. The 12 receptions were one shy of his career high. It was his first double-digit reception game since 2010 and surpassed his previous season high of eight catches for 80 yards achieved in the season opener against St. Louis.
Palmer said he was worried about not having thrown a ball in practice but credited head athletic trainer Tom Reed and his staff.
"They are the best in the business," Palmer said. "We are fortunate to have them. He (Reed) had a plan from Monday on and we stuck to it. I had 100 percent faith and trust in him that he knew what he was doing and that he and his staff would have me ready to play."
As good as Palmer and Fitzgerald were, the Cardinals' defense shined just as bright on a brisk day with the retractable roof open under cloudy skies.
Inside linebacker Karlos Dansby stepped in front of a Kellen Clemens pass intended for tight end Jared Cook on the second play of the third quarter and returned it 23 yards for a touchdown.
It was the second interception for a score in three weeks for Dansby, who is back in Arizona after spending the previous three seasons with the Dolphins.
Another veteran free-agent addition, pass rusher John Abraham, came up with a stellar play of his own just six minutes later. With the Rams backed up deep in their own territory, Clemens dropped back to pass but Abraham tackled him in the end zone for a safety and a 23-3 lead.
Abraham added a third sack near the end of the game, giving him 11 on the season to surpass Lawrence Taylor and Leslie O'Neal for ninth on the NFL's all-time list with 133.
"I'm just glad we got the win," Abraham said. "Personally, I'm happy because it was one of my goals coming into this year, trying to get to 10 (sacks). Now I'm going to try and walk down (Michael) Strahan at No.5. He had 141 1/2."
Clemens finished the game 16 of 27 for 181 yards with no touchdowns and two interceptions.
Rookie running back Zac Stacy scored on a 1-yard touchdown run for the Rams at the start of the fourth quarter -- just the fifth rushing touchdown allowed by Arizona this season.
Cardinals rookie running back Andre Ellington added a 6-yard touchdown run late in the game following safety Rashad Johnson's interception to complete the scoring.
Palmer was 16 of 17 for 169 yards with one touchdown and no interceptions in the first half, helping the Cardinals take a 14-3 lead.
Palmer led the Cardinals on an eight-play, 80-yard drive to open the game, completing each of his three pass attempts for 43 yards before Rashard Mendenhall ran a power sweep into the end zone for a 3-yard touchdown.
St. Louis countered with a 44-yard field goal by Greg Zuerlien, but the Rams' offense was mostly bottled up by Arizona's seventh-ranked defense.
Palmer, meanwhile, completed his first 11 passes. He thought he had a 17-yard touchdown completion to Jim Dray, but after a review, it was ruled the tight end fumbled the ball inside the Rams' 1-yard line.
That killed an 80-yard drive for Arizona, but it did not deter Palmer and the Cardinals. The defense forced another St. Louis punt and Palmer went right back to work.
Palmer completed seven passes for 48 yards during a 10-play, 80-yard drive just before halftime, capped by a 7-yard scoring pass to Fitzgerald to give the Cardinals an 11-point lead.
It was Fitzgerald's 10th touchdown reception of the season, making him the ninth player in history to record at least five seasons of 10 or more touchdown catches. It was also the 87th touchdown grab of his career, tying him with Andre Reed for 12th place on the NFL's all-time list.
Fitzgerald had eight catches for 71 yards at halftime.
Clemens was 11 of 14 for 141 yards passing in the first half, but the Rams could not run the ball, getting just 28 total yards on the ground against the league's fourth-ranked defense against the run.
NOTES: The Rams were flagged 11 times for 90 yards, which included one on special teams, coach Jeff Fisher said, for the first time in seven games. ... Cardinals K Jay Feely, who was 22 of 24 on field-goal attempts entering the game, was 0-for-2 on Sunday, missing from 50 and 25 yards. ... The Rams sacked QB Carson Palmer just once. DE Robert Quinn had three sacks on Palmer in the season opener, but the one on Sunday was credited to rookie LB Alec Ogletree.