Saints’ defense impresses 49ers coach Jim Harbaugh

After rolling the Saints twice in the past two seasons for 782 total yards and 67 points, the San Francisco 49ers will face a far different defense in the Mercedes-Benz Superdome on Sunday.

In a matchup of two teams that eventually hope to be in line for first-round playoff byes and home-field advantage in January, the Saints and 49ers will at the least be vying for a potential tie-breaking edge.

This time, the Saints, who dropped a 36-32 decision to the 49ers in an NFC divisional playoff game in 2011 and were pounded 31-21 last November in the Superdome, hope to return the favor against the Niners offense.

After the worst season statistically in NFL history a year ago, the Saints rank seventh in total defense under first-year coordinator Rob Ryan. They allow 317.6 yards per game and are fifth in scoring defense at 18.1 per contest.

They also rank third against the pass at 199.9 yards per game.

Niners coach Jim Harbaugh has noticed the transformation.

“I think that, as always, the job you do speaks for itself and (Ryan’s) coached a lot of guys,” Harbaugh said, noting the many injuries the Saints have had on that side of the ball. “He has coached a lot of guys, put them in a lot of different positions, and they understand what he’s trying to get done as a coordinator of the defense.

“That speaks volumes when you can teach that many people to play that many different spots and roles. That speaks volumes right there.”

GETTING IT DONE: Through nine games, the Saints are the only team in the NFL to rank in the league’s top 10 in four key statistical categories — including scoring offense and scoring defense.

The Saints rank second in scoring at 29.4 points per game and fifth in scoring defense at 18.1 points.

They also rank in the league’s top 10 in total offense and total defense. They’re second in offense (422.7 yards per game) and seventh in defense (317.6).

Only two other teams — the Texans and Bengals — rank in the top 10 in both offense and defense. The Texans are ninth (offense) and first (defense), while the Bengals are eighth (offense) and fourth (defense) — but come up short in scoring and scoring defense.

PRACTICE REPORT: Only two players didn’t practice Thursday for the Saints as safety Kenny Vaccaro and tight end Benjamin Watson missed a second day of work with concussions.

LB Curtis Lofton (hamstring/ankle) and DE Akiem Hicks (back) worked on a limited basis after being sidelined Wednesday. TE Jimmy Graham (elbow/foot) and DE Cameron Jordan (ankle) were also limited.

FS Malcolm Jenkins (hamstring), SS Roman Harper (knee) and DE Tyrunn Walker (knee) had full participation once again.

For the 49ers, DT Ray McDonald (ankle) and TE Garrett Celek (hamstring) didn’t practice, while DT Justin Smith (shoulder), S Eric Reid (concussion), TE Vernon Davis (concussion) and WR Mario Manningham (knee) were limited. Reid is a former LSU standout.

DIALING UP 500: When the Saints set a franchise record with 625 total yards in Sunday’s 49-17 belting of the Dallas Cowboys, it was the 15th time they had rolled up 500 yards under Sean Payton since he took over in 2006.

The Saints, who topped last week’s total with 626 yards in a playoff game against the Detroit Lions following the 2011 season, are 11-4 when they pick up 500 yards or more.

Their other 600-yard performance came the week before the win over the Lions when they pounded the Carolina Panthers for 617 yards — helping them set an NFL single-season record with 7,474 yards.

LIGHTS OUT?: The 49ers will make their third visit to the Superdome in the past 12 months, but the first since the lights went out early in the third quarter of their 34-31 loss to the Baltimore Ravens in Super Bowl XLVII on Feb. 3 — causing a 34-minute delay.

On a conference call Wednesday, a reporter jokingly asked Harbaugh, whose team rallied from a large deficit after the power outage, if he had checked on the electricity for Sunday.

Harbaugh replied: “No, I haven’t. … Have you? I guess we’ve got some duties today.”

Payton was asked about the electrical problem as well.

“I was there, and a lot of people pinned it on me,” he cracked. “I still don’t know what happened.”