Linebacker Patrick Willis and wide receiver Ted Ginn Jr. are inactive for San Francisco, while Seattle's leading receiver, rookie Doug Baldwin, is playing despite a sore ankle.
Willis missed his third straight game with a hamstring injury Saturday, while Ginn was sidelined with an injured ankle. In the season opener, Ginn returned a kickoff and punt for touchdowns late in the fourth quarter of San Francisco's 33-17 win over the Seahawks.
The 49ers were also without backup cornerback Tramaine Smith. Wide receiver Braylon Edwards, who was questionable with a knee injury, was active.
Seattle's biggest question was Baldwin, who aggravated an ankle injury in practice this week. Baldwin went through early pregame work and was healthy enough to go. The undrafted rookie out of Stanford leads Seattle with 46 catches.