Justin Smith expected to play

San Francisco 49ers coach Jim Harbaugh said on his radio show Tuesday that he expects All-Pro defensive tackle Justin Smith to be able to play Sunday against the Seattle Seahawks after he suffered an arm injury last week against the New England Patriots.

"Everybody affectionately refers to Justin Smith around here as 'The Cowboy,' " Harbaugh said. "I expect we'll see The Cowboy. Knowing what I know of Justin Smith and the situation, I think The Cowboy will be around, saddled up ... roping and riding. If it's humanly possible, The Cowboy will be out there, roping and riding."

The 33-year-old Smith, a three-time Pro Bowler (2009-11) had an MRI exam Monday.

Smith has an active streak of 185 career starts. His streak ranks third among NFL players, behind Ronde Barber (213) and London Fletcher (197).

He has 66 tackles and three sacks this season. He has 75½ sacks in his 12-season career.

The 49ers (10-3-1), who are 5-0 in prime time this season, can clinch the NFC West title if they win at Seattle (9-5) on Sunday night. San Francisco won the first meeting between the teams 13-6 in Week 7.

After beating the Patriots, San Francisco turns its focus to slowing down a surging Seattle team led by rookie quarterback Russell Wilson, while also trying to keep hold of the NFC's No. 2 seed in an effort to secure a first-round playoff bye. Atlanta holds the top spot at 12-2, while Green Bay is right behind the Niners at 10-4.

Information from The Associated Press was used in this report.