The NFC West leaders thrashed their divisional rivals 29-3 at home earlier in the season, but face a trip to Candlestick Park later today.
The 49ers wide receiver, who recently returned from the Achilles tear, told San Jose Mercury News: "Now it's different. New day, new game. I can't wait to go out there and do what I can do.
"This week is a big week for us. With that [11-1] record, you're supposed to be the top team in the NFL. We'll see on Sunday."
Last season, the 49ers secured a 13-6 home win over the Seahawks.