If Nnamdi Asomugha is the 49ers' most prominent mystery heading into the 2013 season, the Packers passing attack ought to provide a quick answer.
In last year's Week 1 meeting against the San Francisco, quarterback Aaron Rodgers attempted a season-high 44 passes. In the rematch in January, he put the ball in the air 39 times.
More important when it comes to Asomugha, the Packers were in three- or four-receiver formations on 88 percent of their offensive plays in the two losses to the 49ers. In those instances, San Francisco's No. 3 cornerback goes into the game and the nose tackle - this year it will be Ian Williams - comes out.
When the teams met last season, then-No. 3 cornerback Chris Culliver mostly covered receiver Jordy Nelson, and it ended up being a winning matchup for the 49ers.
In the Week 1 game, Rodgers only targeted Nelson twice when Culliver was covering him, according to stats from Pro Football Focus. Nelson caught one pass for seven yards and knocked away a pass to Nelson late in the fourth quarter that sealed the win for the 49ers. In the rematch in January, Culliver gave up one catch for 10 yards, according to PFF, but also was hit with a pass-interference penalty against Nelson.
This year the new No. 3 cornerback, Asomugha, promises to see plenty of Nelson.
"Yeah, he'll probably be on him a good bit of the time," defensive coordinator Vic Fangio said Thursday. "We basically are playing left and right with our corners in the (nickel defense), but they like to line their receivers up from left to right also. So yeah, a good chance that he'll be on him for a fair amount."
Asomugha has been dealing with a collarbone injury suffered Aug. 25 against Minnesota but Fangio said that, barring any setbacks, he'll play against the Packers.
Asomugha, a four-time All-Pro, is easily the 49ers' most well-known free-agent acquisition, but he is coming off of two down seasons in Philadelphia in which he often was beaten deep, and at age 32 his speed is a question mark entering the season. In the preseason, however, Asomugha allowed only one reception. It went for five yards on a third-and-12 play. He did not play in the Aug. 29 finale.
-- Matt Barrows