ST. LOUIS (AP) — A blow to the head turned Kurt Warner into a spectator in the second half, still in uniform but shut down for the day.

The Arizona Cardinals quarterback said it was just a precaution for what the team termed concussion-related symptoms. In any case, he'd already done enough to make it three straight victories over his former team in the stadium where he rose to stardom.

Warner threw for 203 yards and two touchdowns while building a 21-3 cushion, and the NFC West leaders hung on late, remaining unbeaten on the road with a 21-13 victory over the St. Louis Rams on Sunday. Arizona had a season-high 183 yards rushing, including 110 on 14 carries by Tim Hightower for the Cardinals' first 100-yard game of the season.

"I felt pretty good coming out right after halftime, but I just wanted to be smart," Warner said. "It was one of those situations where I didn't feel perfect."

Warner doesn't recall having a concussion since 2003, when he was hurt in the Rams' opener. That also was his final start with St. Louis.

"I've had a couple of minor concussions, very minor, nothing that's been prolonged," Warner said. "So not a state of panic. I feel good. I think I'm going to be just fine, but we'll take it day by day and we'll see."

The Rams drove to the 7 late in the game needing a TD and a 2-point conversion to tie. Marc Bulger threw incomplete for Donnie Avery in the end zone on fourth-and-4 after some jostling from Arizona's Dominique Rodgers-Cromartie.

"We'll just go with the ref's call and hopefully next time it'll go our way," Bulger said.

The Cardinals (7-3) have won six of seven.

"We were hitting on all cylinders. We were making some big plays, and I think we had them off-balance a little bit," Warner said. "When we're clicking and in rhythm, that's how we can play."

Steven Jackson became the first Rams player to post five consecutive 1,000-yard seasons, gaining 116 yards on 24 carries with a fourth-quarter touchdown that capitalized on tight end Anthony Becht's lost fumble, cutting the deficit to eight points. It's also the fourth straight 100-yard game for Jackson.

The Rams (1-9) showed life in the second half after a miserable start, but are 0-4 at home after losing to the Cardinals for the sixth straight time. Earlier this season they became the first team in NFL history to face three straight unbeaten teams at home, losing to the Vikings, Colts and Saints, and management purchased more than 4,000 tickets to sell out the game and avoid a local TV blackout.

"We just came out really flat," Jackson said. "Against a team like Arizona, it's really hard to overcome that."

Warner was 15 for 19 and usually had plenty of time in the pocket. The four incompletions came on two balls he threw away, a third that was batted down and a fourth on a left-handed attempt while in the grasp of defensive end Chris Long.

It appeared Warner was hurt by safety O.J. Atogwe's high hit on a blitz that drove the quarterback's head into the turf. Warner lay on the field for a few seconds before getting up and stayed in the game for the last six plays of a 90-yard drive capped by Beanie Wells' 1-yard run.

Coach Ken Whisenhunt was unaware of Warner's past concussion history, adding, "He's started over 30 games for us and he hasn't missed much."

"What you don't want to do," Whisenhunt added, "is jeopardize games down the road."

Matt Leinart took over after a late turnover at the end of the half, and Arizona mostly sat on the lead. That was enough to make Warner 5-2 against the Rams, with whom he became a storybook star while leading the team to two Super Bowls in three years from 1999-2001. He's 26-4 at the Edward Jones Dome, including 4-0 in the playoffs, with 67 touchdown passes and 34 interceptions.

The Cardinals stumbled early when Warner and Wells missed connections on a pitchout for a lost fumble at the Arizona 25, leading to a Rams field goal. The rest of the half was all Arizona, with Hightower gaining 91 yards on eight carries, Anquan Boldin catching seven passes for 96 yards and his first TD since Week 3, and Larry Fitzgerald catching six passes for 71 yards and a score.