After playing the Houston Texans in the preseason for the past four years and holding joint training camp practices from 2008 through 2010, there’s not a lot the New Orleans Saints don’t know about their neighbors from the west.

But there is one thing that’s new about the Texans going into Sunday’s noon meeting against the Saints in the Superdome — their defensive philosophy.

Even that isn’t completely unfamiliar to the Saints, however, as they’ve matched up with the trademark 3-4 scheme of new Texans defensive coordinator Wade Phillips the past two seasons.

What’s different is the Texans (2-0) will be coming in with lots of confidence on defense when they face the Saints (1-1).

The Texans, who ranked 29th in scoring defense (26.7 points per game), 30th in total yards allowed (376.9) and 32nd in passing yards (267.5) a year ago, rank first in all three categories after two games.

After going against two offensively challenged teams in Indianapolis and Miami to begin the season, however, the Texans will take a step up in class against the Saints.

The Saints offense ranks fifth in scoring, total yards and passing yards, setting up an interesting matchup.

Even though they faced the Dallas Cowboys when Phillips was the Dallas Cowboys’ head coach in 2009 and also went against his base defense in November after he was fired, the Saints must be ready for whatever the former Saints defensive coordinator has in store.

“It’s a completely different look than 2010 with this team,” Saints coach Sean Payton said, “so most of the film study is off the two regular-season tapes and the preseason.

“We’re also able to go back and look at Dallas tape and get a feel for, more than anything else, where the alignments are, what fronts they want to play, what coverages they want to play.”

Even the preseason is a bit of a mystery, however.

The Saints didn’t show a lot on offense, while Phillips kept a lot of stuff under wraps in the Texans’ 27-14 win over Payton’s team in the second exhibition game on Aug. 20 in Reliant Stadium.

“The one thing you see (in the regular season) is they’re doing a good job of not giving up the big plays,” Payton said. “They’re getting off the field on third down and they’re rushing the passer very well.”

The Texans, who’ve given up just 271.0 yards and 10.0 points per game, have allowed a first down on just 5 of 21 third-down conversion attempts (23.8 percent). They also have five sacks after collecting 30 last season.

Saints quarterback Drew Brees, who was with the San Diego Chargers for two of Phillips’ three seasons as their defensive coordinator, isn’t surprised by what he’s seen — even if stats often are skewed this early in the season.

“That doesn’t surprise me at all,” Brees said. “Like I said, I have a lot of respect for (Phillips). I know he’s a great coach, and they’re playing very well right now.

“They just play with a lot of confidence,” he said. “They believe in their system and are playing fast. There are some guys that are obviously playing some different positions than they have in the past, just being that it’s a 3-4 defense, and they seem to be embracing that role.”

One of those players is outside linebacker Mario Williams. As the first pick in the 2006 draft, Williams played his first five seasons as a defensive end and excelled with his hand in the ground in piling up 48 sacks.

The 6-foot-6, 283-pound Williams has shown some of the same skills in his new role as a standup linebacker, however, and already has two sacks.

“He still does a lot of the same things, it’s just a matter of him having his hand on the ground or not,” Brees said. “He’s a big, big physical presence and is very athletic for as big as he is.”

Williams is a big part of the strength of the Texans’ defense as he and third-year pro Connor Barwin flank a pair of active inside linebackers in Brian Cushing and DeMeco Ryans.

“Typically, what comes with (3-4) is a a different front and a lot more pressure, and the way they’re able to bring it from everywhere with everybody,” Brees said.

But the Texans also shored up their leaky pass defense with the addition of Johnathan Joseph, one of the top cornerbacks in free agency, and veteran free safety Danieal Manning.

“Well, it makes you feel real good,” coach Gary Kubiak said of the early results from his defense. “I think we’re surprised at how quick the process has taken place with no offseason, and really, Wade just having those guys for seven or eight weeks.

“When you watch the work that’s taking place every day, the energy we’re playing with, how hard we’re playing, you know why you’re getting much better results.”

Texans quarterback Matt Schaub is excited after having to match other offenses score-for-score for years, much like the Saints had to do before defensive coordinator Gregg Williams arrived in 2009.

“It’s been exciting to watch them, especially once we got to the regular season and got to see them live situations and get after it a little bit,” Schaub said. “It’s been great to see them play and go cut it loose because we knew what we had havin gone against them in training camp.”