"He got a pretty good pull," Bears general manager Jerry Angelo said. "We'll know more (today), but we're not real optimistic that it's going to be a few days. It's probably going to be longer than that. We'll see for sure. (It's) unfortunate, but it gives us a chance to look at the backups. We'll get a good look-see now (at others)."
Angelo said Urlacher -- a four-time Pro Bowler who has led the team in tackles in each of his four seasons in the NFL -- will have an MRI today on his right hamstring, which was injured during non-contact drills.
Urlacher wasn't on crutches after practice when he passed reporters on his way to the cafeteria for dinner, but had the area heavily taped. He refused comment.
"We'll do the (whole) nine yards (on checking it out)," Angelo said. "He pulled it pretty good."
The injury to Urlacher spoiled an otherwise upbeat day for the Bears, who began a new era Wednesday under new coach Lovie Smith. The team finally came to terms with its first-round pick, Oklahoma defensive tackle Tommie Harris, on a five-year deal, and inked its third-round pick, Fresno State receiver Bernard Berrian, to a four-year deal.
Urlacher's injury, however, overshadowed everything.
"Hamstrings, they need rest," Smith said, referring to Urlacher. "He'll have to sit out, which he won't like. It's going to be weeks, probably."
The good news is, the Bears have 45 days until they open up their season against the Detroit Lions on Sept. 12. Urlacher, who has 680 career tackles, has played in 62 of 64 games during his career. He could be out weeks or possibly a month or longer.
"What can I say? Brian's a great player and a big part of what we're trying to do," Smith said. "He's down, (but) he didn't have a season-ending injury. We talked about developing our depth at the (middle) linebacker position. (Now) we're going to have to do it a little quicker than we wanted to."
With both sides of the ball putting in new schemes with a revamped coaching staff, this wasn't what the Bears needed on Day 1 under the new regime. Now the team drops quite a few notches in talent with second-year player Hunter Hillenmeyer and undrafted rookie free agent Jeremy Cain looking to get plenty of reps.
Angelo also said second-year linebacker Lance Briggs, who starts on the outside, could be bumped inside to help out for the time being, as well as former Purdue linebacker Joe Odom, who worked with the first-team defense Wednesday on the outside.
"It obviously will slow us down right away, but again it gives us a chance to look at our depth," Angelo said. "Injuries happen. We've seen first-hand here, and how we respond to injuries is a big part of having a successful season and that's our goal.
"You don't expect (injuries like this), because guys come in such great shape. We've worked very hard in the offseason, and these guys are in top physical shape. But those things happen and we've got to go on."