Observation deck: Seahawks-Raiders

SEATTLE — For the second consecutive year, the Seattle Seahawks end the preseason undefeated.

That and $4 will get you a Starbucks coffee across the street from Pike Place Market, but the Seahawks will take it and use the momentum to start a season of high expectations and Super Bowl predictions from many experts and fans.

Seattle defeated the Oakland Raiders 22-6 Thursday night at Century Link Field in the typical battle of backups for the final preseason game.

What it means: The Seahawks look like a team ready to contend for the championship. The defense allowed only 36 points in the four preseason games. The biggest problem for the coaches is determining who makes the 53-man roster on what might be the deepest team in the NFL.

Stephen Williams suffers concussion: The one big downer of the night. The receiver has been the biggest surprise on the preseason on offense with his ability to out-battle defenders on deep throws down the sideline. He did it again Thursday, but this time the end result was costly.

Williams made a leaping 50-yard catch on Seattle’s opening drive, out-clawing Oakland defender Phillip Adams for the ball on the long pass from Russell Wilson. But Williams fell backward on the catch and slammed his head into the turf, resulting in a concussion.

That makes Williams’ status for the season opener uncertain. There is a protocol of tests he must go through before getting an OK to practice or play. The good news is that he has 10 days before the opener in Charlotte, N.C., against the Carolina Panthers.

No worries at kicker: Steven Hauschka was perfect against Oakland, making five field goals, including three of more than 50 yards -- a 56-yarder in the first quarter, a 51-yarder in the second and a 53-yarder in the fourth. Hauschka also had five touchbacks on kickoffs.

Jermaine Kearse sees all: Wide receiver Kearse should be the poster boy for Lasik surgery. He was close to perfect in the preseason after having the Lasik procedure in the offseason to improve his vision and end his days of wearing contact lenses. Kearse had two more receptions in the third quarter Thursday, including a 33-yard sideline catch. He ended the preseason with two touchdown catches and a 107-yard kickoff return for a TD.

What’s next: The Seahawks open the regular season at the Panthers on Sept. 8. Seattle defeated Carolina 16-12 last October in Charlotte, but the Seahawks have lost their past two season openers, both of which were on the road.

Seattle is 7-5 in its past 12 season openers, but 2-5 in the past seven openers on the road. Next week’s game will be the 10th time the Seahawks have started the regular season on the road in the past 14 seasons.