LAKE FOREST, Ill. – It was only one game against an inept and undermanned opponent, but Sunday’s dominant performance was exactly what the Bears defense needed moving forward.

After allowing an average of 30.5 points and 376 yards in its previous four games, the embattled unit completely shut down the St. Louis Rams in a 27-3 win at the Edward Jones Dome.

Defensive end Alex Brown flattens quarterback Trent Green Sunday in the Bears' 27-3 win over the Rams.

The Bears generated five sacks to match their total from the previous five games while also registering four interceptions for the second time this season.

“It was a confidence booster for the defense and for the line,” said defensive end Adewale Ogunleye, who recorded two sacks. “It’s been a long time coming. I knew it was going to come, it was just a matter of time. We needed it and hopefully we’ll use it as momentum.”

The line accounted for all five sacks as Tommie Harris matched Ogunleye with two and Alex Brown had one. It was the most sacks by Bears linemen since they also had five on Sept. 30, 2007 in a 37-27 loss in Detroit.

“Our defensive line did a great job rushing the passer all day,” said coach Lovie Smith. “We got the sacks, but they harassed [the quarterback] most of the day. They are the engine of our defense, so it was good to see that.”

The relentless pass rush Sunday was not the result of any strategic adjustments.

“It’s always about execution,” Smith said. “As far as did we change our defense, throw it out and start over? No, we played our defense and played it a lot better than we’ve been playing.”

The defense started quickly, dropping the Rams for losses on four of five plays on their first possession and on eight of 12 snaps in the first quarter overall. That included five rushes for minus-eight yards and three sacks.

“We talk about playing with energy and playing hard," Smith said, "and the guys did that from the start.”

“There were a lot of things we did in a positive manner [early] and I think that got the guys juiced up, and they continued to play hard throughout the game,” said defensive coordinator Bob Babich. “They never let down even when we got up by a bunch at the end of the game.”

The Bears did not allow a touchdown for the first time since a 17-6 win at Oakland on Nov. 11, 2007, and permitted the fewest points since a 10-0 road win over the New York Jets on Nov. 19, 2006.

The Rams offense entered the game ranked 29th in the NFL and was missing two of its best players in running back Steven Jackson (thigh) and tackle Orlando Pace (knee). St. Louis was further depleted when quarterback Marc Bulger exited with a head injury in favor of Trent Green after being sacked by Ogunleye on the Rams’ first drive.

Bears linebacker Lance Briggs celebrates after one of his two interceptions in Sunday's win in St. Louis.

Ogunleye entered the game with 2½ sacks and nearly matched that total with one sack on each of the Rams’ first two possessions. Harris added his first sack on the final play of the first quarter.

“That was big for us to get after the quarterback early,” Ogunleye said. “We’ve been struggling and I’ve been kind of trying to get some sacks and that was a big statement for us. It was momentum and it kept going throughout the rest of the game.”

The Bears defense also stuffed the Rams running game, allowing just 14 yards on 19 carries. Two weeks earlier, Chicago had limited the Titans to 20 yards on 29 attempts. But in between those two games, the Packers gashed the Bears run defense for 200 yards on 38 carries.

“We had a down week and that was something we wanted to correct,” Ogunleye said. “We’d been playing the run really well this season, so that’s not a surprise. But after last week against Green Bay, we wanted to refocus on that, and that’s what we did.”

The defense’s confidence wasn’t wavering before Sunday, but players were puzzled and frustrated with their inability to perform as well as expected.

“You say it so many times, but until you actually do it, it doesn’t sit firm in your mind,” Ogunleye said. “Now I think guys know that we are capable of playing good defense, and not just for a quarter or a half. Throughout the whole game, we were dominating.”

It couldn’t have happened at a better time, not with a first-place clash against Pro Bowl running back Adrian Peterson and the Vikings looming Sunday night in Minnesota.

“It’s just a confidence booster going into this week,” Brown said. “We have a very good [opponent], a team I believe that is better than the team we just played, so we’ve got to be ready.

“It just gives us a little more confidence understanding that if everybody does their job, this type of stuff can happen. We played well, we played hard. I’m pretty sure there are some things that we need to correct, but hopefully we can correct those things and keep playing at this level. We’re going to need it for the next five games.”