GREEN BAY -- For 30 delightfully dominant minutes, it looked as though the Packers were going to stomp on San Francisco with such force that coach Mike McCarthy would be able to rest his starters in the second half in preparation for the upcoming Turkey Day trip to Detroit.

Then -- as fast as you can say "Ouch!" -- that plan changed and the forecast beyond Thanksgiving became ominously cloudy.

Leading by 20 points after a 362-yard first half, the Packers hung on for a 30-24 victory before a sellout crowd of 70,445. The victory, which improved Green Bay's record to 6-4, came with two disappointing footnotes.

Make that "knee notes."

Linebacker Aaron Kampman and cornerback Al Harris -- who are pivotal performers on a Green bay defensive unit that seemed to be hitting its stride during the past eight days -- were carted from the field after suffering left knee injuries.

Kampman, who sat out last week's victory against Dallas with a concussion, was injured rushing the passer against San Francisco Adam Snyder midway through the third quarter. Later, Harris was injured trying to defend 49ers rookie receiver Michael Crabtree.

The National Football Post, which is partly-owned by Harris' agent, reported that Harris suffered a torn anterior cruciate ligament and will be out for the season.

The severity of Kampman's injury was not immediately known, but it's likely he'll miss at least two weeks.

"Injuries have kind of fallen upon us," McCarthy said. "It's unfortunate. You don't want to see any of your players get hurt, but it's part of our job. That's really a big part of a coach's responsibility to overcome these types of situations."

With Harris and Kampman shelved, it seems likely that fans will see more of rookies Brandon Underwood and Brad Jones.

"The two rookies had a chance to play today, and it'll give them a chance to learn from being in there," McCarthy said. "You know, Brad had a chance to play some last week, so he'll have two games to work off. And Brandon, it was obviously a big opportunity for him, so we'll just keep coaching them."

After allowing just one first down and 57 net yards in the first half, the Packers' defense began to falter in the second half. 49ers quarterback Alex Smith, who was chosen ahead of Aaron Rodgers in the 2005 draft, began to connect with tight end Vernon Davis (the Packers could have had him instead of A.J. Hawk) and rookie wide receiver Michael Crabtree (Green Bay took B.J. Raji over him).

"I think we came out (in the first half), for whatever reason, apprehensive, cautious and kind of waiting for somebody to make a play," Smith said "We really didn't get going at all until the second half."

49ers coach Mike Singletary called the loss "disappointing," but was encouraged by his team's offense in the wake of a sluggish start.

"You have to play 60 minutes and you have to start fast, whether you're on the road or you're at home," he said. "We have to learn how to come out and be ready to go from the start."

The Packers seemed ready to go -- but not score -- when they settled for field goals twice in the opening quarter en route to a 23-3 lead.

"We came out a little flat in the second half," running back Brandon Jackson said.

The numbers ended up being impressive. Rodgers (32 for 45) passed for 344 yards and two touchdowns with a quarterback rating of 108. Ryan Grant rushed 21 times for 129 yards, with several of them coming on a victory-clinching drive that ate up the final 6 minutes after the 49ers closed within six points.

"You've got to give credit to our guys up front," Rodgers said. "RG (Ryan Grant)... had a good rhythm today as far as being patient, hitting the holes and breaking tackles. And, the receivers do a great job blocking for him when he gets to that second level as well."

Notebook: The Packers controlled the ball for 41 minutes 39 seconds and collected 26 first downs.... Green bay has won 12 of its last 13 games against San Francisco... Packers wide receiver Greg Jennings caught his third touchdown pass of the season. He had nine last year.... Green Bay's 484 yards of offense was a season high.... San Francisco, which entered the game ranked third in the league against the run, had not allowed a first-possession score before Mason Crosby's field goal in the first quarter.