RENTON — This isn't a second chance.

Mike Williams is past all that after coming back to establish himself as a starting NFL wide receiver last season with the Seahawks.

Sunday will be an opportunity for Williams, though, as he returns to the lineup after sitting out last week's game against Cincinnati with a sore hamstring.

"He's ready to get back in and battle," coach Pete Carroll said. "He's going to play a lot this week."

Williams was one of the biggest surprises for Seattle last year when he led the team with 65 catches. This season, he is one of the Seahawks' biggest mysteries. How does he fit on this team?

Seattle signed Sidney Rice as a free agent with the belief he could be the team's No. 1 receiving option. He has finished with more than 100 yards receiving in two of the five games he has played.

Williams — who has missed two of the past three games because of injuries — was supposed to be the other side of that equation. He has nine catches in the five games he has played at a position with as much competition as any on the roster.

Ben Obomanu started in Williams' place last week, and he caught four passes for 107 yards.

"He came through and did a very nice job," Carroll said of Obomanu. "It's a competitive position for us; we've got a lot of guys that we like getting on the field."

That includes second-year receiver Golden Tate, who has made strides in practice but hasn't seen that translate into opportunities in the game. And there's another name to factor in: Deon Butler.

Remember him? Seattle's third-round pick in 2009 made an impact last season when he caught 36 passes. He had five receptions at San Francisco on Dec. 12, matching his career high, before suffering a compound fracture in his right leg.

Butler began this season continuing to rehabilitate and on the physically unable to perform list. He has been eligible to come off the past three weeks but has not been activated, and Carroll indicated that won't happen before Sunday's game.

Seattle has a Tuesday deadline to activate Butler for this season.

And that's just one of the many roster variables Seattle is juggling.

Tight end Cameron Morrrah is questionable because of a sore knee that kept him from practicing this week. So is defensive tackle Alan Branch, who has started all seven games but has been slowed by a leg injury. David Vobora, Seattle's primary backup at linebacker, strained his calf in practice Thursday and will be a game-time decision.

Quarterback Tarvaris Jackson is listed as probable, which means there is a virtual certainty he will be available for normal duty. That doesn't mean he's healthy.

"He does not feel great," Carroll said. "He's barely making it through practice, but he did. He did make it through."

So did Williams, who was full-go in practice Friday and is expected to get a chance Sunday to show where he fits into this offense.

Note

• CB Mike Jenkins (hamstring) and RB Felix Jones (ankle) have been ruled out for Dallas, which means rookie DeMarco Murray likely will start his second consecutive game.

Danny O'Neil: 206-464-2364 or doneil@seattletimes.com