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ARLINGTON, Texas -- The only drama at the end of this one was whether rookie DeMarco Murray would set the Dallas Cowboys' franchise rushing record, a remarkable feat considering it's gone from Hall of Famer Tony Dorsett to NFL rushing king Emmitt Smith.

Murray indeed pulled it off, running through a shoddy St. Louis Rams defense for 253 yards, including an early 91-yard touchdown that got the Cowboys started toward a 34-7 victory on Sunday.

Murray ran for the most yards in the NFL this season and the ninth-most in league history. His touchdown was the second-longest run in team history, topped only by the NFL-record 99-yarder by Dorsett in January 1983. He also had the most yards ever against the Rams, replacing Jim Brown on that list.

"I never thought in a million years that I'd ever have a day like this," Murray said. "This is what I've been working hard for since my Pop Warner days."

As impressive as Murray's performance was, it came against the Rams, who fell to 0-6 and came in with the NFL's worst defense against the run. They had allowed 163 yards per game, more than two first downs more anyone else.

The holes were so plentiful that when Murray took himself out to catch his breath in the fourth quarter, fourth-stringer Phillip Tanner finished that drive with 35 yards on the first four carries of his career, capping it with a 6-yard TD run. St. Louis wasn't even able to exploit a line featuring a starting left guard who was unemployed as of Monday.

"It's easy to run the ball when you're not making tackles," Rams safety Quintin Mikell. "When you're not getting guys on the ground, there's not much you can do."

For Dallas (3-3), the real satisfaction was ending a two-game losing skid and emphatically breaking a stretch of 11 straight games decided by four points or less.

"It was the first one where we could take a knee to win," receiver Miles Austin said. "It's a good feeling."

The Cowboys never trailed and left no reason for team owner Jerry Jones to criticize coach Jason Garrett's play-calling -- except maybe to wonder why Murray didn't have a bigger role in the offense until this game.

Get this: Murray didn't even start against the Rams.

With lead back Felix Jones out with a high ankle sprain, Tashard Choice trotted out first. The plan was for him to share the load with Murray, a third-round pick whose development was slowed because he missed most of training camp with a hamstring injury.

It took all of one carry for Murray to become the main option.

On a first-and-19 from the Dallas 9, Murray went through a giant hole on the left side, cut through an attempted ankle tackle, then outran Mikell. It was a heck of a way to score the first touchdown of his career, and it more than doubled his career rushing total of 71 coming into the game.

Murray had 187 yards through three quarters, and the Cowboys were up 20-7. Because they wanted to run to protect the lead, it was clear that Murray would get a shot at Smith's club record of 237 yards set Oct. 31, 1993, at Philadelphia.

Murray followed with a 43-yard run that could've gone for a 73-yard touchdown had he not run out of gas along the way. He finished it 2 yards shy of Smith's mark.

"I just wanted to get down and protect the ball," he said.

The record fell on his next try, an 8-yard run. He finished with 25 carries and an average of 10.1 yards. Dallas ran for 294 yards overall, spiking a season average of 84.8 that had been among the league's worst.

For the local fans, it was a terrific start to a baseball-football doubleheader between teams from Dallas-Fort Worth and St. Louis. Game 4 of the World Series began just down the street less than an hour after this game ended. Josh Hamilton of the Rangers and Lance Berkman of the Cardinals showed up in uniform as honorary captains for the pregame coin toss.

The Rams were the perfect foe for the Cowboys to cure all that ailed them. In addition to their trouble stopping the run, they were without quarterback Sam Bradford (high ankle sprain) and were averaging the fewest points in the league even with him.

A.J. Feeley made his first start since 2007 and was 20 of 33 for 196 yards with one interception and one sack. But the offense gained only 4 yards in the third quarter, and had only two good drives. The first ended in a 6-yard touchdown run by Steven Jackson that got St. Louis within 14-7. The other ended with a fourth-and-goal from the 1 that was stuffed in the final minutes.

"We couldn't get any rhythm and left the defense on the field entirely too long," Jackson said. "For whatever reason, this keeps being the same old story."

Jackson finished with 70 yards, 46 coming on the touchdown drive.

Brandon Lloyd caught six passes for 74 yards in his St. Louis debut. He was acquired from Denver earlier this week.

St. Louis also saw right tackle Jason Smith and backup defensive tackle Darell Scott carted off. Both were taken to a hospital for evaluation and were expected to fly home with the team. Smith, a Dallas native, had a strained neck; Scott's injury was called a blow to the head.

Dallas' Tony Romo was 14 of 24 for 166 yards, with two touchdowns. He didn't have to throw much because the running game was doing so well. However, he hit Dez Bryant for four passes and a touchdown in the second half, which was significant because they'd hooked up for only two catches after halftime all season. Romo's other TD throw went to Jason Witten.

Game notes

Dallas rookie kicker Dan Bailey made two field goals, including a career-best 51-yarder, giving him 16 in a row. ... Brown had 237 yards against the Los Angeles Rams in 1957. ... Murray's 91-yarder also was the longest against the Rams. ... Both teams came in with a single rushing TD. Only Kansas City had less. ... The Cowboys haven't allowed a first-quarter touchdown this season. ... Ronnie Dunn sang the national anthem, just like he did the night before at the World Series.