After nine years as a starter and three Pro Bowl appearances, Dallas’ Tony Romo is nothing if not a pretty decent quarterback.

But his chances of looking like much more than that when he and the Cowboys host the Saints on Sunday night grow dramatically if New Orleans fails to do one thing: Contain Dallas running back DeMarco Murray, who through three weeks topped the league in rushing yards (385) and was in a six-way tie for the lead in rushing touchdowns (3) heading into Thursday’s Washington-New York Giants game.

“It makes it hard for the secondary (to defend a passer like Romo) because ... they’ll run, run, run, run here — and then the next thing you know they’re going over the top,” said Corey White, who started his first game this year for the Saints (1-2) at the No. 2 outside cornerback position in a 20-9 victory over Minnesota on Sunday. “So you’ve got to keep your eyes (open).”

The 6-foot, 214-pound Murray has served up plenty of advance notice about his ability as the Saints prepare to clash with a Dallas team that’s 2-1. The four-year pro was 10th in the NFL last season with 1,121 yards on 217 carries (an average of 5.2 yards per rush, which was fourth-best in the league). His nine touchdowns on the ground entered him into a five-way tie for sixth place in the league.

Murray is in even better form to start off this season. He carried the ball 22 times for 118 yards and a touchdown in a 28-17 defeat at home against San Francisco. Then, to help Dallas to a 26-10 win at Tennessee and a 34-31 triumph at St. Louis, Murray rushed for a combined 267 yards and two TDs.

Three lost fumbles by Murray are a sizable blemish on his performance so far. Nonetheless, that doesn’t diminish the danger he presents, said outside linebacker Parys Haralson, who logs many snaps in run defense.

“You can’t just go in (solely committed to) punching the ball out, or he’s going to run clean through you,” Haralson said. “They’ve been working on it with him and trying to get it fixed. That’s part of the game — you watch the film, see what you do wrong and correct it.”

Outside linebacker Junior Galette added that the level of production Murray’s had has a two-fold effect. First, it coaxes defenses into dedicating seven players to stopping the run, resulting in unfavorable matchups to the personnel tasked with defending the pass. A quarterback such as Romo (completing 67.4 percent of his passes for 674 yards, four touchdowns and four interceptions) can exploit that.

“You load the box up because you’re scared of and want to stop the run, and that’s when you can have a good quarterback turn elite,” Galette explained.

A big day from Murray would also logically limit the number of times Dallas would need to pass. That would cut back the chances to sack Romo and pressure him into interceptable throws, something for which a pass-rusher such as Galette lives.

“If you don’t stop the run, then you might get 10 (chances for pass) rushes in a game,” said Galette, who leads the Saints with two sacks. “It’s going to be hard to get anything in 10 rushes.”

The Saints can take heart in the fact that their defense had allowed what was tied for the ninth-fewest rushing yards through three weeks. Furthermore, since defensive coordinator Rob Ryan arrived in New Orleans in 2013 from Dallas, they’ve already tasted success against Murray.

The Saints held Murray to 89 yards and a touchdown on 16 carries in a 49-17 rout of Dallas in New Orleans in Week 10 last year. In the second half of that contest, Murray had a paltry nine yards on five carries.

But the Saints are realistic about the circumstances of that game. They’re fully aware Dallas abandoned its running game after falling behind 28-10 at halftime. Murray became a non-factor as Dallas attempted to pass its way back into a game in which New Orleans set an NFL record for first downs (40) and a franchise mark for yards on offense (625).

All of which is why a defense that had given up the 24th-most yards overall through three games is readying itself in earnest to stop Murray possibly without the benefit of a comfortable lead.

“People in our league ... know that he’s someone who’s got strength, who’s got power,” Saints coach Sean Payton said. “He’s been a big weapon for them.”