After watching the Detroit Lions remain unbeaten Monday night with a 24-13 victory over the Chicago Bears, here are some of my initial thoughts about the upcoming game against the 49ers (4-1):-- Adam Snyder is going to see a lot of Lions defensive tackle Ndamukong Suh, who lines up every play over the right guard.-- The 49ers' offensive line will be tested. And not just Snyder. The Bears were called for nine false starts at Ford Field. The crowd should be worked up for this game featuring teams that are a combined 9-1 this season. (By the way, these same teams were a combined 1-9 last year at this same point).-- The Lions had nine defensive linemen active for Monday's game. They are able to keep the line fresh as part of their rotation. They'll be coming at the 49ers in waves.-- The 49ers' nickel defense was on the field for just 26 snaps against the Tampa Bay Buccaneers. The 49ers will have to go with five defensive backs against the Lions, who line up with three wideouts -- Calvin Johnson and rookie Titus Young, along with slot receiver Nate Burleson -- nearly every play.-- That means rookie defensive end Aldon Smith will rarely come off the field in this game. He'll be matched mostly against left tackle Jeff Backus, an 11-year pro who has started all 165 games of his career. (By the way, yes, I called Aldon Smith a "defensive end," because he has yet to play outside linebacker this season). Smith, the No. 7 overall pick, leads the 49ers with 3.5 sacks.--In the 49ers' nickel package last week, Aldon Smith, safety Reggie Smith and rookie cornerback Chris Culliver entered the game, replacing nose tackle Ricky Jean Francois, outside linebacker Parys Haralson and strong safety Donte Whitner.--Calvin Johnson is now the best wide receiver in football. He is the first player in NFL history to have nine touchdowns catches through five games. The folks at "Monday Night Football" put up a graphic that showed Johnson is 6-foot-5 with a 6-10 wingspan. His standing reach is 8-foot-8, and his vertical leap is 45 inches. His maximum reach is an amazing 12-5. All quarterback Matthew Stafford has to do is throw the ball within the size of a two-car garage, and Johnson can go get it.--The 49ers haven't yet had cornerback Carlos Rogers shadow the opposition's top receiver. Will this be the week? If it's not, the 49ers have a big decision to make with their third cornerback. Is Culliver, coming off a strong showing against Tampa Bay, ready to be matched against Johnson from time to time? Or will Shawntae Spencer, who missed last week's game with "turf toe" bump the rookie to the sideline?--Safety Dashon Goldson had some big hits the past two weeks. He'll be tested Sunday, as the Lions love to get the ball deep. Johnson is a big target for Stafford. That means he's also a big target for Goldson.--Detroit, yes, Detroit will be the center of the football world on Sunday.