IRVING, Texas — When a four-year starter leaves and his backup takes over, there's supposed to be lots of angst and questions, even more when the team seems to hedge its bets by spending its top pick on a guy who plays the same position.

Well, usually. The way things have gone with the Dallas Cowboys making Marion Barber their featured running back is among the exceptions.

Barber backed up Julius Jones the last several years, but the understudy was the star. Two years ago, "Marion the Barbarian" led the conference in rushing touchdowns; last year, he made the Pro Bowl. By season's end, Jones was the starter in name only, and it was no surprise the Cowboys let him leave as a free agent.

The transition actually started in the playoffs, when Dallas let Barber start. He ran for 129 yards, which made management so giddy that he got a $45 million contract extension before training camp. In between, the Cowboys took Felix Jones with the 22nd overall pick, but it was only to pair his speed with Barber's power, not to have a just-in-case starter.

So far, it's all worked out perfectly.

Barber is coming off a 28-carry, 142-yard performance that went a long way toward helping the Cowboys win at Green Bay. On a night when Tony Romo wasn't at his best, and the Packers throttled Terrell Owens, Dallas wore down the defense by giving the ball to Barber.

"I think he demoralizes the other team in a lot of ways," coach Wade Phillips said. "He keeps pounding and keeps going and, all of a sudden, he's busting out of there for 10, 12, 15 yards, or he is making a 1-yard run into an 8-yard run."

Or, he leaves the defense vulnerable to the change of pace when Jones gets his turn.

It happened in the opener, when Barber hurt his ribs and Jones zipped through a hole for an 11-yard touchdown on the first carry of his career. He showed his speed the following week with a 98-yard kickoff return for a touchdown, then burned the Packers on a 60-yard touchdown run. Even with the nice blocking that helped clear his path, defenses might've gotten to Barber. They had no chance of catching Jones.

Behind this 1-2 punch, the Cowboys are averaging 150.7 yards rushing per game. With a passing attack that's also clicking, it's no wonder the Cowboys are 3-0 and lead the NFL in total yards, placing second in points scored.

"You're lucky to have the ability to have guys who take the pressure off you at every position," Romo said. "The wide receiver is lucky to have a good offensive line because he has the ability to get downfield on different routes. The tight end is lucky to have a wide receiver that takes the coverage off of them. I'm lucky enough to have all of them. We're lucky in that sense. I think that's something we all appreciate and understand. We don't take it for granted."

While waiting for his contract extension to be worked out, Barber was with agent Drew Rosenhaus in Miami. Owens has the same agent and he saw how hard Barber was training.

"He prepared himself for the role that he possesses now," Owens said. "He knew that it was going to be a situation where he was going to be an every-down back and he works hard at it. I think everybody kind of foresaw what he was going to be able to do just by the split time that he had between he and Julius last year."

What impresses Owens most about Barber's play so far is that he's done it despite the lingering pain in his ribs.

"That shows you the toughness that he has," Owens said.

A Barbarian, just like the nickname T.O. bestowed upon him.

"I thought maybe last year it was just because he was alternating and towards the end of the game he was real fresh and strong, but that's not the case," Phillips said. "He is a tremendous force for us out there. Any time it's third-and-1 or goal-line or things like that, you just feel sure he is going to make it every time — and he seems to do that."