Reggie Bush is licking his chops at the thought of facing the Bears’ porous run defense that has been downright poor this season. “Well, yeah,” the Lions running back said. “We have to be able to take advantage of obviously the holes that we see. Obviously they’re going to do their part this week at trying to plug up some of those holes. And it’s our job to try to exploit some of those. “We feel like there is some room for us to take advantage of them in the run game. We just have to make sure we go in and play fundamentally sound.” Taking advantage of holes in a defense is one thing. But what the Bears (5-3) have more resembles craters the size of the Grand Canyon. The run defense already was suspect when Bush and the Lions ran all over them for a season-high 159 yards Sept. 29 at Ford Field. On Sunday at Soldier Field, the Bears likely will be without seven-time Pro Bowl linebacker Lance Briggs. But even with Briggs, Bush tore up the Bears in their last meeting with 139 rushing yards — the only time Bush has topped 100 on the ground this season. “We didn’t tackle him,” Bears coach Marc Trestman told Detroit reporters on a conference call. “No. 1, we didn’t fit the run well, and No. 2, he played exceptionally well and he made people miss. “He’s a difference-making player in the run and the pass. We’ve got to do a better job this time in working this week to try to neutralize him.” That’s the goal, of course. But judging from what Chicago did — or didn’t do — at Green Bay on Monday, the Bears’ tackling still is a major issue. Packers running backs Eddie Lacy and James Starks combined for 190 yards and gashed the Bears for runs of 56 and 32 yards, respectively.