By Adam Hoge-

BOURBONNAIS (CBS) Brian Urlacher was once again not on the field Tuesday, missing his sixth consecutive practice.

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The linebacker is battling soreness in his left knee — the one he injured in last season’s finale — and it is odd that he isn’t even standing on the sideline.

Head coach Lovie Smith said after Monday’s practice that Urlacher “has a personal matter going on,” but there’s growing speculation that Urlacher’s knee issue is more serious than first believed. Smith didn’t exactly sound encouraging when he said Monday: “I feel pretty comfortable about him playing this year.”

Asked Tuesday afternoon about his teammate, cornerback Tim Jennings didn’t mention anything about a “personal matter” and admitted that he’s starting to get concerned about Urlacher’s knee.

“At first it wasn’t too much of a concern on my part,” Jennings said. “I can only speak for myself and I always ask Brian how he’s feeling. ‘Are you going to go today?’ Nah, he’s going to keep him out still got a little soreness. And you get a little concerned about it because we know how bad Brian wants to be out there, how hard he works to be out there, so when you see him not out there with us after so many practices, it draws a little bit of concern just because we care about him and we need that piece of the puzzle so badly.”

Originally, Urlacher was just supposed to miss a couple of practices to rest the knee, but now the Bears are just hoping he’ll be back for the season opener Sept. 9.

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“When it’s coming down to getting ready to get the season started, we kind of want to know what’s going on,” Jennings said. “If we feel like it’s not too serious and we can get him by Week 1, then that’s fine with us.”

Jennings also admitted that Urlacher is concerned about it, too.

“He’s been very positive and he’s just a little sore and he’s a bit concerned about it so right he just wants to get that out of the way and make sure he’ll be ready for Week 1.”

Smith was mum regarding the Urlacher injury after Tuesday’s practice, saying only that the linebacker was out again for “personal reasons.”

Urlacher hasn’t practiced since July 31.

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For live updates from Bears training camp, follow Adam on Twitter @AdamHogeCBS.