No one was more surprised by the ugly turn of events on the field and in the stands Sunday at the Mercedes-Benz Superdome than former New Orleans Saints safety Roman Harper, now in his first season with the Carolina Panthers.

On the field, the Panthers dominated from start to finish, winning 41-10 in a landslide to further throw the NFC South into a jumbled mess.

In the stands, many of the sellout crowd of 73,006 openly turned on the Saints as the deficit mounted, sending them off to their dressing room at halftime with a cascade of boos. Then, early in the third quarter, after running back Jonathan Stewart extended the Panthers’ lead to 31-3 with a 69-yard touchdown run, a fan hurled a plastic beer bottle on to the field, narrowly missing players and officials.

“I’ve never seen anybody throw a beer from the top row,’’ Harper said. “I mean where are we at, man, the WWE or something? It’s crazy. I know the fans are better than that, and I would expect better from them. That could have hit somebody.’’

Moments after the projectile landed near the Poydras Street end zone, the stadium’s public address announcer encouraged fans to act responsibly, display good sportsmanship and refrain from tossing objects on to the field or suffer the consequences.

“You got to be smarter as fans and respect the game for what it is,’’ said Harper, a second-round pick in coach Sean Payton’s fledgling 2006 draft class. “They’re frustrated, and I understand that. They were probably a little tipsy, the one who threw it. But we got to be better than that. New Orleans has to be better than that.’’

Later in the third quarter, fans cheered enthusiastically when Panthers quarterback Cam Newton was slow to get up after absorbing a hard, clean hit from Saints defenders Kenny Vaccaro and Curtis Lofton.

“I heard the boos when the Saints were going through hard times out there,’’ Panthers weakside linebacker Thomas Davis said. “But I also heard the cheers when our quarterback got hurt.

“That’s disgraceful.’’

The game was a little chippy from the outset and took on a different tone after Newton’s 2-yard touchdown run with 6:41 remaining in the first quarter to increase Carolina’s lead to 17-0. Players from both teams scuffled in the Girod Street end zone, and the fracas spilled over into the tunnel.

After restoring order, officials ejected Panthers tight end Brandon Williams for throwing a punch, and assessed a personal foul against Lofton.

In the end, the Panthers (4-8-1) avenged an earlier 27-10 loss to the Saints in Week 9 and kept alive their chances of defending their NFC South crown. The Saints (5-8) suffered their fourth consecutive loss at home and fell a half-game behind division leader Atlanta (5-7).

“I didn’t hear the ‘Stand Up & Get Crunk’ song all day,’’ Harper said, smiling. “Going in, I wouldn’t have said that was going to happen, so it was great, man. How many times does Drew Brees not throw three touchdowns in the dome? It just doesn’t happen. For 3½ quarters, we had him in lock down.

“We did a great job of making them boo by halftime, which is always a great thing when you’re the visiting team ... to go on the road, in a tough environment, and win the way we did. As a fan, I would be kind of frustrated, too. But it’s not like they’re sober. So it is what it is.’’