As the Vikings prepare for Sunday's game with San Francisco, we asked Eric Branch, the 49ers beat writer for the San Francisco Chronicle, to give us his scouting report. Here are four things you need to know ...

1 The 49ers' defense has been in a groove. Which could be scary for a Vikings offense that has scored only 13 points before halftime the first two weeks.

The Packers managed only 45 yards rushing in the opener against San Francisco, their longest rush a 9-yard scramble by Aaron Rodgers. Detroit averaged just 3.2 yards on its 26 rushes with Matt Stafford delivering the long rush for 11 yards.

"The defense has been incredibly successful at making teams one-dimensional," Branch said. "Eventually, they wear opponents down to where they sort of surrender and say, 'What's the point in even trying to run against this team?' "


2 Randy Moss hasn't been incredibly productive through two weeks (five catches, 61 yards, one TD). But he has fit in well.

"He's been a model teammate to this point," said Branch, noting Moss' impressive football intelligence and his willingness to mentor the 49ers' younger receivers.

Moss' playing time has been down in the first two games -- which leads to the inevitable worry that he might soon get frustrated with how much he's being used.

"I do think his role will expand as the season goes on,'' Branch said. "I get the sense that the 49ers are aware that he's 35 years old and are wondering just how much juice his legs will have in January if they play him too extensively early on. So it's been calculated with the way they're managing his time."

3 Jim Harbaugh has been a significant upgrade in the head coaching position over predecessor Mike Singletary.

"It was perplexing," Branch said. "As a player he was legendary and he was known for being one of the film junkies and a guy who could pick up on all these tendencies of an offense. That was a big part of what made him so great. But as a coach, he even said himself he was more of a big-picture guy. And he wasn't as consumed with the details, which may have hurt. He was never really that strong with X's and O's."

4 So what has been Harbaugh's brilliance?

"He has his players' back at all times, almost to a ridiculous extent," Branch said. "Guys want to play for him. They believe in him and they appreciate the value of his loyalty. ...With Singletary, I got the impression that behind the scenes his intensity and his personality began to wear thin. And they maybe began to tune out some of the rah-rah, motivational talks they got."