Rod Marinelli playing big role in Bears' success

That's hardly a surprise.

Smith and Marinelli are longtime friends and Chicago's defense is performing as well as any heading into Monday night's game against the Detroit Lions.

It helps having Pro Bowl players such as Julius Peppers and Lance Briggs, but don't underestimate the impact of their defensive coordinator.

"I couldn't do Rod justice by saying just one thing that he does," Smith said. "He does so much. Again, I know I talk about this always, I've known him so long and I've seen him in every situation. He's just a great man, great coach, great leader. We could spend the rest of the day talking about him. He's such a valuable part of what we're doing here."

What they're doing at the moment is impressive, and the defense is a big reason why Chicago leads the NFC North at 4-1.

The Bears are holding opponents to 291.2 yards per game and rank third overall on defense. They're tops against the run, lead the league in interceptions (13), are tied for fourth in sacks (18) and the defense has done its share of scoring, too.

That group has five touchdowns this season — all on interceptions in the past three games — and has given up just five TDs to opposing offenses.

Unsung players such as cornerback Tim Jennings (four interceptions, 14 pass breakups) and defensive tackle Henry Melton (4 1/2 sacks) have come up big, and a line that was a big question mark has created more than enough chaos.

And a big reason for all that is Marinelli. Now in his third season as coordinator and fourth on the Bears' staff, the Bears jumped at the chance to hire him as the line coach even after an awful three-year run as Detroit's head coach.

He was fired after the Lions went 0-16 in 2008, but he was also a logical fit for Chicago. After all, he was friends with Smith and knew the Cover-2 defense.

"We just learned it from the floor up together," Marinelli said. "Trying to understand it and see it, the details that go into the system. When all the details and fundamentals that go in and how to drill it. I think it's the real belief, we have a great belief in what we do and how we do things. We kind of grew up in it with coach (Tony) Dungy and his belief obviously is very strong in it. We've always been tied to the system and how to do things."