BOURBONNAIS -- The Brian Urlacher mystery is no closer to being solved.
The eight-time Pro Bowl middle linebacker was back in camp, but he did not practice Saturday after being excused for personal reasons for the previous three practices and Thursday night's preseason opener.
He has not practiced since July 31.
"Brian Urlacher is back after he's taken care of some business," coach Lovie Smith said. "So it's good to get him back on the practice field, even though he's not practicing yet.
"He still has some soreness with the knee. Exactly when he'll be back, I can't tell you that."
Urlacher, who suffered sprained ligaments in his left knee in the 2011 season finale, has missed eight straight practices. Smith was asked if Urlacher had additional tests on the knee during his absence.
"The knee is sore, and he's been gone for personal reasons," Smith said. "That's all we're going to really talk on the subject."
No longer left out:
The competition for the starting left-tackle job may be back on, after it appeared J'Marcus Webb had won the job, almost by default, from Chris Williams.
Webb had gotten all the first-team reps in the week leading up to Thursday's preseason opener, but he did not impress offensive coordinator Mike Tice with his performance in the game.
So Saturday Williams got some reps on the left side with the first team. He had been occasionally spelling starting right tackle Gabe Carimi, and he played there with the second team Thursday.
"Just (like) every other decision we make," coach Lovie Smith said of the switch. "We had a chance to see guys in certain situations from the game, and we'll continue to look at different people."
Williams has started for the Bears at both positions and at left guard.
"Coach (Tice) told me get some work at left tackle today, that was it," Williams said after practice. I just do what I'm told, man. Just go out and work. It'll work itself out."
Center and line leader Roberto Garza said watching the film of Thursday's 31-3 preseason loss wasn't enjoyable.
"It shouldn't be," he said. "We didn't do a lot of things good, and we have to learn from this. Obviously this week of practice is important, and this next game is, too. Any time you're on the field, you have to be ready to play. Nobody's job is really secure."
The Bears allowed 6 sacks and generated just 132 yards of total offense.
Backup linebacker and special-teams player Dom DeCicco did not practice Saturday and is out indefinitely with a groin injury.
"Dom has done some good things," coach Lovie Smith said, "but he's going to be on the shelf for a while."
Backup guard Chilo Rachal also missed practice with general soreness, as did linebacker Jabara Williams (hamstring) and defensive tackle DeMario Pressley (foot).
Rearranging deck chairs:
Linebackers Xavier Adibi and K.C. Asiodu and defensive end Aston Whiteside were signed Saturday but did not practice. Defensive tackle Ronnie Cameron and cornerback Jeremy Ware were waived.
Adibi played in 38 games and started eight with the Houston Texans (2008-10) and Minnesota Vikings (2011). Asiodu played in a total of 11 games with the St. Louis Rams (2009) and New Orleans Saints (2010). Whiteside was signed this season by the Dallas Cowboys as an undrafted free agent out of Abilene Christian University.