Middle linebacker Brian Urlacher was held out of practice Sunday for the fourth straight day, but the Bears are simply being cautious with a veteran to whom preseason participation isn't a priority.

"His knee is still a little sore," coach Lovie Smith said. "Hopefully, we'll be able to get him back out here before long. But we'll take our time with Brian."

Urlacher suffered partial tears to the MCL (medial collateral ligament) and PCL (posterior cruciate ligament) in his left knee during the 2011 regular-season finale at Minnesota. His offseason activity was severely curtailed.

There is some trepidation over any lengthy absence from practice with the season opener just over a month away, especially when it concerns a seven-time Pro Bowl player at a position that has little depth.

"There is always concern when you have an injury at the end of the year and you miss some time in the offseason, but he should be OK," Smith said. "It's not like he really hurt it anymore. You assume -- I assume -- he would have some soreness and he would miss a few of these training camp practices."

Urlacher is not expected to play in Thursday night's preseason opener against the Broncos at Soldier Field.

Asked about the possibility of an arthroscopic procedure to evaluate the injury, Smith said: "We're on top of his knee. When he's ready to go, he'll be back out there. That's about all we'll talk about."

The Bears signed veteran Geno Hayes but Nick Roach has taken most of the first-team reps with Urlacher sidelined. Dom DeCicco can also play the middle, but the second-year man has only 12 career tackles and isn't ready to be thrust into the middle of the Chicago defense.

Another alternative to consider if Urlacher is lost for a longer period of time is sliding Lance Briggs from his spot on the weak side. Briggs played middle linebacker at Arizona and knows the defense as well as any veteran on the roster.