RENTON — Your fourth string offensive tackle isn’t supposed to see the field, but for the Seattle Seahawks there’s a chance he’ll be protecting the injured, exposed rib area of starting quarterback Matt Hasselbeck on Sunday. Against none other than the NFC West Division champion Arizona Cardinals, fresh off a February Super Bowl appearance.

Perhaps the Seahawks can take solace in the fact that Arizona is ranked dead last in the league in pass defense, with just eight sacks for the season.

Still, Kyle Williams, one of only two healthy offensive tackles available — right tackle Ray Willis is the other — on Seattle’s 53-man roster, likely will have his hands full on Sunday if his name is called.

With limited reps during practice last week, Williams had to rely on mental reps and film study in terms of his preparation for Jacksonville after starting left tackle Brandon Frye left the game in the first quarter with a left shoulder injury.

Just a couple of plays later, Williams had an added distraction — he sprained his knee on Olindo Mare’s 47-yard field goal, but had to suck it up and play because at that point Seattle had only five offensive linemen healthy, with left guard Mansfield Wrotto suffering an ankle injury and Steve Vallos subbing in for him.

“No one said anything,” Williams said. “I mean, we knew. We had no choice. I had to play.”

Seattle has three starting offensive linemen out again this week. Starting offensive tackles Walter Jones (knee) and Sean Locklear (ankle) and left guard Rob Sims (ankle) will not be available until the first game after the team’s bye week, on Nov. 1 at Dallas.

And coach Jim Mora said on Monday that the team did not know the full extent of Frye’s shoulder injury, leaving open the possibility he may not be available on Sunday.

But in Williams, Seattle has a guy with experience. The 6-foot-6, 295-pound USC product joined the Seahawks in 2007 and spent the entire year on the practice squad. Williams also spent most of 2008 on the practice squad before being elevated to the active roster in late November, starting at left tackle the final two games of the season with Jones and Locklear both finishing on the injured reserve list.

The experience for Williams was invaluable, both in helping to build confidence that he can play at this level and giving him a sense of familiarity for what it’s like to play on Sundays.

Hasselbeck said he trusts Williams to get the job done if his name is called.

“Kyle has been in our program a long time,” Hasselbeck said. “He really knows what he’s doing. I think guys have a lot of confidence in him.”

Extra points

Mora said Hasselbeck appeared to be OK on Monday and will not have any limitations in practice this week. … Cornerback Ken Lucas played with a heavy heart on Sunday. His father, Clyde, died unexpectedly on Friday, but he still chose to play. Clyde Lucas was diagnosed with lung cancer in 2003. … Defensive lineman Michael Bennett, whom the Seahawks waived to make room for Kyle Williams on the active roster on Saturday, was picked up by Tampa Bay. … Mora said Safety C.J. Wallace has a hamstring strain and will have an MRI test Wednesday. Mora said Wallace could miss some time this week. Cornerback Travis Fisher (hamstring) should be OK, along with Wrotto (ankle) and Williams (knee). Patrick Kerney (groin) is expected to return this week. Mora said LB Leroy Hill might see some limited practice time this week, as he readies for a potential return to the field on Nov. 1.

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