The eight-year veteran was at the 49ers practice facility on Monday -- a players' day off -- and showed no ill effects of an injured middle finger on his throwing hand.
Head coach Jim Harbaugh showed a bit of concern about the injury to his starting quarterback's throwing in his Monday press conference, but cited Smith's toughness as a reason to be optimistic.
"Alex is . . . it's well-documented how tough he is. He talks about it not being a big deal. We'll see."
Smith threw for 303 yards and three touchdowns in the 49ers 45-3 win over the Buffalo Bills in Week 5.
Kickoff for the rematch of last year's NFC Championship is scheduled for 1:25 p.m. PT at Candlestick Park and the game will be televised on FOX.