Jim Harbaugh and Jim Schwartz shook hands, smiled and offered each other sweet-natured "good games" before this one started. But it's been a knock-down, drag-out, dogfight - complete with eye gouging -- ever since.
So far the 49ers are winning the battle, 14-6.
Long, methodical marches marked their Week 1 win in Green Bay. In this one, the 49ers didn't waste much time. On their opening drive, they gained 29 yards on a misdirection run by Mario Manningham, which fooled Lions left defensive end Cliff Avril.
On the next play, Alex Smith connected with Michael Crabtree for 17 yards and on the play after that, he saw Vernon Davis on a mismatch with safety John Wendling, who was filling in for injured starter Louis Delmas. Smith connected with Davis for 21 yards, and the 49ers were in the end zone in 72 seconds.
On the ensuing drive, the Lions were aided by a 33-yard pass interference penalty against cornerback Chris Culliver that gave them the ball at the San Francisco 26-yard line. Four plays after that Jason Hanson knocked in a 38-yard field goal, the first of his two field goals of the half.
The 49ers' second touchdown drive began when Matthew Stafford's third-down pass sailed well over his intended receiver's head and was intercepted by a diving Dashon Goldson. The 49ers settled for a 35-yard David Akers field goal on the drive, but the Lions crashed into the kicker on the attempt, giving the 49ers a first down.
Randy Moss drew a pass-interference penalty in the end zone against another Detroit substitute, cornerback Jacob Lacey, that gave San Francisco the ball on the 1-yard line. On the next play, Frank Gore powered in for his second touchdown of the year.
Davis, who played all but two snaps against the Packers in Week 1, missed chunks of two first-half drives after getting poked in the eye by defensive end Avril. Just before he left the game, Davis and fellow tight end Delanie Walker tangled with Avril near the 49ers sideline, with all three of them going down in a heap. Davis returned later in the half and seemed to show no ill effects.
The 49ers' defense, meanwhile, has been in its nickel package for most of the half. They've only been in their base defense - which includes nose tackle Isaac Sopoaga - for six plays.
The Lions have countered with more ruins than perhaps is their custom (12 vs. 16 pass attempts), and they have 45 rushing yards at the half. But have gotten no farther than the San Francisco 20-yard line. That drive occurred after Kendall Hunter fumbled a kickoff.
-- Matt Barrows