Posted by ESPN.com's Mike Sando from Seattle
Patrick Kerney, working on the right side of the Seattle defense, has sacked Alex Smith and forced him to fumble. Seattle takes over at the San Francisco 21. The 49ers are playing without starting left tackle Jonas Jennings. They've been quite happy with rookie Joe Staley at right tackle; he has been their most consistent offensive lineman by some accounts. Adam Snyder is working on the other side, and he's having some problems already. Crowd noise is an issue here. Kerney has been the starting left end this season, but he's working the other side tonight.