SANTA CLARA -- If the 49ers are to beat the Seattle Seahawks in their home stadium Sunday night, defensive coordinator Vic Fangio said Wednesday it's imperative the team tackles better than it did in its 34-28 opening victory against Green Bay.

It's a given the 49ers must find a way to contain elusive quarterback Russell Wilson and rugged tailback Marshawn Lynch, but Fangio said execution may be even more important in the passing game.

"What happened in last week's game, we missed a lot of tackles on receivers," Fangio said. "We've got to be able to tackle these guys after the catch. The (Seahawks) have excellent runners after the catch in (Golden) Tate, (Doug) Baldwin and (Sidney) Rice, plus their tight ends and backs on checkdowns and screens. So the tackling in the passing game is going to be just as important."

Asked to assess veteran cornerback Nnamdi Asomugha's first performance with the 49ers, Fangio was mostly complimentary.

"He had good big plays, he had some big plays for us on a couple of third downs," Fangio said. "He also missed a tackle or two that hurt us, so he had some good and some bad."

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