QB Alex Smith sprains finger

Updated: October 7, 2012, 9:21 PM ET

By Mike Sando | ESPN.com

SAN FRANCISCO -- San Francisco 49ers quarterback Alex Smith suffered a sprained middle finger on his throwing hand while making his final pass attempt during a 45-3 victory over the Buffalo Bills on Sunday.

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Smith was seen entering the X-ray room adjacent to the 49ers' locker room. Coach Jim Harbaugh was not far behind, but he turned back before entering and headed into the postgame interview room nearby. Harbaugh said during his news conference he wasn't sure which finger Smith had injured, or how badly.

Smith emerged a few minutes later. He wore a light wrap on the finger during his postgame news conference. He said he thought the finger might be sprained, but he was not certain. He did not sound concerned.

Smith topped 300 yards passing while leading an offense that set a franchise record with 621 yards.