It will be interesting to see how coach Marc Trestman and the undefeated Bears deal with their first dose of adversity this week at Detroit.
The Bears (3-0) will be without their Pro Bowl 3-technique defensive tackle Henry Melton. After a slow start, Melton was having his best game of the young season before he suffered a torn ACL in his left knee Sunday that will keep him sidelined until next season.
Disruptive play at the 3 technique (the tackle who lines up shaded off the outside shoulder of the guard) is critical to the success of the Cover-2 defense.
Melton had become that type of player, capable of penetrating across the line of scrimmage to scuttle run plays and of pressuring the quarterback on pass plays.
If you're looking for the positive here, it's worth noting that the Bears are undefeated despite not getting much of a contribution from Melton or the defensive line.
That position was not considered a deep one, even before Melton's injury. Now it will rely even more heavily on 33-year-old end Julius Peppers, who also started very slowly but, according to Pro Football Focus, had his best game of the season Sunday at Pittsburgh.
If Peppers still possesses Pro Bowl talent, the Bears need it now more than ever.
Third-year nose tackle Stephen Paea has been the Bears' highest-rated defensive lineman this season, according to the team and Pro Football Focus. Without Melton lining up next to him, his job becomes more difficult.
Nate Collins will take Melton's place in the starting lineup. He has performed well as a backup and last week played 41 snaps, eight more than Melton, who was hurt early in the fourth quarter.
But moving Collins to the starting lineup leaves little depth. The Bears were impressed by the performance of undrafted rookie Zach Minter in training camp and the preseason, and now he will get an opportunity to get on the field after being inactive the first three Sundays.
That still leaves just three tackles on the roster, and there are none on the practice squad, though that could change this week.
Under Lovie Smith, the Bears preferred to rotate four interior defensive linemen, but this year it has been a three-man rotation. It remains to be seen if three can handle that workload over the course of an entire season.
There aren't any difference-making defensive tackles the Bears can sign off the street, but they'll try to add a veteran this week, although a trade is unlikely.
General manager Phil Emery allowed Israel Idonije to leave in free agency, even though Idonije could have been signed at a bargain rate.
The versatile veteran, who was a valuable contributor at end and tackle in his nine seasons in Chicago, would be a godsend at this point, but he now plays for the Lions.
Melton's loss isn't the Bears' only defensive concern-- not by a longshot.
Cornerback Charles Tillman's health is iffy at best after he rested a groin injury in the fourth quarter Sunday.
He missed two days of practice last week with a knee injury. According to Pro Football Focus, Tillman's performance against the Steelers was his worst in three years.
But the 6-foot-2, two-time Pro Bowler may be the most irreplaceable member of the Bears' defense, especially when the opponent is the Lions and 6-foot-5, 236-pound wide receiver Calvin Johnson.
"Megatron" led the NFL last season with 122 catches and 1,964 yards. He dominated just about everyone he encountered -- except Tillman.
Johnson's worst game of 2012 was against the Bears, when he caught just 3 passes for 34 yards at Soldier Field, with Tillman shadowing him throughout. Even in the rematch at Ford Field, Johnson caught just 5 passes for 72 yards.
His 106 yards in two games against the Bears were fewer than half the 261 yards he had against Minnesota and Green Bay last season and less than he averaged for each game against the rest of the league.
If Tillman can't play Sunday, a little adversity could become a major catastrophe.
But the Lions won't feel sorry for the Bears. They have their own problems, which include the broken arm suffered by No. 2 wide receiver Nate Burleson early Tuesday. He was trying to save a pizza from falling off the seat of his car and drove into a median.
•The Bears on Tuesday terminated the practice-squad contracts of quarterback Jerrod Johnson and offensive tackle Jamaal Johnson-Webb and signed defensive end Cheta Ozougwu and offensive tackle Roger Gaines to the practice squad.
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