On an almost perfect Monday night for Alex Smith, the San Francisco 49ers flexed their NFC West dominance with a 24-3 flattening of the...

GLENDALE, Ariz. — On an almost perfect Monday night for Alex Smith, the San Francisco 49ers flexed their NFC West dominance with a 24-3 flattening of the Arizona Cardinals.

Smith completed 18 of 19 passes for 232 yards and three touchdowns — two to Michael Crabtree and one to Randy Moss — to help San Francisco (6-2) open a two-game lead in the division and send Arizona (4-4) to its fourth consecutive loss.

Smith’s only incompletion was dropped by a wide-open Delanie Walker in the first half.

“Eighteen of 19, I have never seen that,” San Francisco coach Jim Harbaugh said. “How important for your quarterback to play very well? It is very important and I don’t know how you play much better. It was a fantastic game by him.”

Arizona defensive tackle Darnell Dockett could hardly believe what Smith had done.

“Everyone’s surprised. My 5-year-old son’s surprised,” Dockett said. “But at the end of the day it wasn’t like he had to make the long perfect throws. He had some guys open and we missed some tackles and they made plays.”

Smith was 14 of 15 for 146 yards and two touchdowns, both to Crabtree, as the 49ers built a 17-0 halftime lead.

Moss caught a 47-yard TD pass, dodging tacklers down the sideline on a play that seemed to turn back the clock to the receiver’s prime. He tied Terrell Owens for fourth on the NFL career touchdown list with 156.

Smith, who tied a career high with the three touchdown passes, spread out his completions to 10 receivers.