Tait originally injured his groin during an off-season workout and it has never fully healed.
In the meantime, Mitchell will remain the starting left tackle. His first real test will come Thursday when the Bears travel to St. Louis to play the Rams in the preseason opener.
"We haven't been displeased with how he's played," Lovie Smith said of Mitchell "We're talking before the first preseason game and we're still looking at our best combination."
Tait sat out the afternoon practice to rest his groin injury, which has been his routine on days the Bears have two practices.
The only competition on the offensive line that appears to be undecided is right guard. The three-man derby between Terrence Metcalf, Ruben Brown and Mike Gandy will come down to the exhibition season.
Metcalf has received the most reps with the starting unit and appears to be the favorite to win the job.
Injury Update: Alfonso Boone sat out both practices on Monday because of a knee problem. At this point the Bears don't believe it's a serious injury, but are giving him at least a day to rest.
Dustin Lyman had to leave practice this morning because of a right knee injury. Lyman, who has been plagued by left knee injuries throughout his career, hurt his right knee. An MRI didn't reveal any structural damage, so he could return to practice as soon as tomorrow.
"I'm so sick of having to explain injuries," Lyman said. "I don't want to miss one day."
Take the day off: Rex Grossman didn't throw a ball in the morning practice. The Bears are scheduling rest periods for their quarterbacks in an effort to rest avoid arm soreness. Jonathan Quinn took a day off last week.
Grossman returned in the afternoon and threw the ball well, including connecting with David Terrell for a 60-yard touchdown pass.
"My arm feels as good as it has ever felt," Grossman said. "Taking this morning off, coming back this afternoon I feel pretty good."
Kicking off the Competition: It seems GM Jerry Angelo has been trying to replace Paul Edinger since he took the job as general manager three years ago. Edinger is unlikely to be beaten out by newly acquired placekicker Remy Hamilton, but the former Arena Bowl veteran did have a strong showing in a kickoff drill.
Hamilton had all six of his kickoffs reach the end zone and most were more than a couple yards deep. Edinger reached the end zone of five of six attempts, but didn't match the hang time of Hamilton.
With the team deciding not to put Jerry Azumah on Injured Reserve, it's even more unlikely the Bears could afford to carry a kickoff specialist.
"The master plan isn't to keep two kickers, but if we have two very good kickers we think can help us win, you never know. It's impressive what he can do, especially with onside kicks and he has a strong leg as far as kickoffs are concerned," Smith said of Hamilton. "Right now, we would like competition at all positions and now we have some competition at our kicker position."
First Impression: Eric Kelly had an inauspicious debut for the Bears. The new acquisition got beat by Ahmad Merritt for a big gain in the morning practice and came back in the afternoon only to have Jamin Elliott go over him on a jump ball that resulted in 30-yard reception.
Change in Plans: The Bears have cancelled Tuesday's morning practice that was scheduled to begin at 8:40 a.m. The team's only practice will begin at 3:55 p.m.