ST. LOUIS — After scoring on its first nine possessions in last week’s 62-7 record-setting blowout of the Indianapolis Colts, the New Orleans Saints offense was poised to have another successful outing Sunday.

Going into their game with the St. Louis Rams, the NFL’s top-scoring team and second-ranked offense figured to pad its gaudy stats against a defense that ranked 31st in points allowed and 29th in total yards.

Yet, it was the other way around.

Instead of the previously winless Rams taking in on the chin, the Saints offense struggled throughout the day in a disappointing 31-21 loss in the Edward Jones Dome.

The Rams did a number on the Saints in the first half, recording three of their six sacks of Drew Brees and holding his offense to 94 total yards en route to building a 17-0 halftime lead.

While 17 points is certainly not an insurmountable deficit for the Saints, it was on Sunday as the Rams pushed the margin to 24-0 in the third quarter and kept the pressure on Brees and his offense the rest of the afternoon.

One of the most disconcerting things to Saints coach Sean Payton was the six sacks, the most in his 88-game tenure as head coach, which put his team in some tight situations — particularly on third down.

“Look,” he said, “when you’re getting a sack on second down, and now it’s third-and-14, what do you want to call?”

It was like that for much of the day for the Saints, who were a respectable 8-of-17 in third-down opportunities. The problem, he said, was there were way too many third-and-10 or longer situations.

The Saints had third-down plays measuring 10, 12, 14, 19, 22 and 24 yards and converted just one of them — the third-and-12 on a 25-yard pass from Brees to wide receiver Marques Colston.

“I felt like the start of each drive we’d get the first down, and usually, that’s when things start to roll,” said Brees, whose team managed 283 yards — their lowest total of the season by 99 yards. “We’d get hit with a 2-yard loss on a run play, we’d get a sack, and here we are at second-and-12, second-and-17. “We’re trying to work our way back and maybe there’s a penalty. So, when I say third-and-longs we had some third-and-15, third-and-17 — there’s just not that many play calls from that distance.”

“Just going to third-and-10 or more, we almost ran out of plays,” Payton said. “When that’s happening, you’re not winning the early downs, you’re not getting the yardage you really want on the early runs. And you’re not getting the yards you want and efficiency you want in the passing game.”

The Saints wound up netting 56 yards and a 2.8 average on 20 attempts against a team that ranked last in the NFL in allowing 183.8 yards per game. In last week’s 34-7 loss at Dallas, they were pounded for 294 rushing yards.

“Negative plays, that’s on us,” left tackle Jermon Bushrod said of the offensive line. “We run the ball on first and second down and we lose 4 yards, we lose 3 yards. Automatically, we’re in second-and-long or third-and-long, and they’re pinning their ears back.”

Long was a word they didn’t like to hear for more than one reason as Rams defensive end Chris Long barged past Saints right tackle Charles Brown for two of his three sacks.

“It felt good, everybody rushed well,” said Long, who doubled his season total of three in one game. “It takes three or four guys to rush well. The entire front rushed well, and our offense gave us the lead.”

Bushrod and backup Pat McQuistan, who had to go in after Brown injured his knee in the fourth quarter, also gave up sacks as the Rams did most of their damage with a four-man rush.

“I have to watch the film because I don’t know who exactly gave up the sacks or what the situation was,” left guard Carl Nicks said. “They schemed the hell out of us. They got off the ball and were ready to play, and we weren’t today.”