MINNEAPOLIS -- Suddenly, the Seahawks' highly touted rookie class is mired in injury questions.

Already playing without top pick L.J. Collier, a defensive end out of TCU who remains out indefinitely with a high ankle sprain, the Seahawks learned last week that touted receiver DK Metcalf has a knee injury that will require surgery that will occur Tuesday. Safety Marquise Blair left in the third quarter of Sunday's 25-19 loss to the Vikings with back spasms.

Seahawks coach Pete Carroll said it was unclear if Blair's injury will cause him to miss any time. He was carted off the field after leaving the game in the third quarter. Carroll said his back felt tight and continued to tighten.

"I don't know what that means right now (for the future)," Carroll said.

Carroll insisted that Metcalf may be able to be back for the regular-season opener against the Bengals on Sept. 8, saying "there's optimism."

Carroll declined to say the exact nature of Metcalf's injury other than to say it was discovered last week when Metcalf had issues with his knee in practice.

"We are disappointed for him because he was off to a fantastic start, but I don't think this is going to derail him for long," Carroll said. "But he does have to have some work done, and we will know more when we get back into town."

Asked why there is optimism he won't be out long, Carroll said because "the docs really have a clear look already at the MRI, what it is and think it's a really quick recovery, likely. That still all has to happen. I think we are going to keep him in town and get the work done right away and be very optimistic about the way he can get back."

Metcalf practiced during the week, including the final practice that was open to the media Friday.

Metcalf missed the team's mock game at Pop Keeney Stadium in Bothell on Aug. 3 with an oblique injury. He recovered to play five days later in the preseason opener against the Broncos, making one catch for 8 yards on four targets, all in the first half, from Paxton Lynch.

Metcalf was selected by the team in the second round of the 2019 draft and garnered immense hype for performances in the rookie minicamp and other offseason workouts and was expected to contend for a starting spot.

Metcalf has a history of injuries, playing just 21 of 36 games in his three years at Mississippi.

Blair was already having tough night, as he appeared to be the player beaten on Minnesota's only TD in the first half, a 3-yard pass from Sean Mannion to Irv Smith.

Blair has had a slow start to being integrated into the defense after missing a lot of the offseason program with a hamstring injury.

SHAQUEM GRIFFIN STAYS BACK IN SEATTLE WITH BRUISED KNEE

Second-year linebacker Shaquem Griffin didn't make the trip because he's dealing with a bruised knee that he suffered in the preseason opener against Denver.

Carroll didn't offer much more in the way of specifics about the nature of the injury or when Griffin may be back when he talked to the media after the game.

"He had a knee that he came back from last week that it just kind of got reaggravated," Carroll said. "So he just, he had stared with a bruise and that's what I know about it right now."

Griffin was held out of practice early last week, returned to practice at midweek, talking to reporters Thursday and didn't indicate there were any issues. He was held out again late in the week as Carroll said the injury had flared up again and the team needed to take a closer look at it.

Griffin, a preseason sensation a year ago, got off to a nice start in the preseason opener, forcing a fumble on the opening kickoff. But he suffered the bruised knee during the game and played just 14 defensive snaps.

Griffin is considered in a battle for a spot on the 53-man roster as the Seahawks drafted two linebackers, Utah's Cody Barton and UW's Ben Burr-Kirven.

WAGNER, WRIGHT SIT WHILE WILSON AND THE REST OF STARTERS PLAY

The Seahawks held out two veteran players: linebackers Bobby Wagner (who was expected to play after missing most of the past two weeks to have a platelet-rich plasma injection in his knee) and K.J. Wright (who has been practicing but was held out after missing much of last season with a knee injury suffered in a preseason game on this same field in Minneapolis).

Cody Barton started again at middle linebacker and Austin Calitro started at weakside linebacker.

But otherwise, the Seahawks played their starters substantially throughout the first half in contrast to the opener against Denver when Seattle sat out 13 players listed as starters on the depth chart.

Seattle went with what would be its starting defense -- minus Wagner and Wright -- for basically all of the first two series before subbing.

That meant players such as safety Bradley McDougald and tackles Jarran Reed and Poona Ford, who sat out the opener, saw their first action of the preseason.

The Seahawks replaced many starters in the third series, leaving in most of the starting secondary. But by the fourth series, the Seahawks had taken out every defensive starter other than strongside linebacker Mychal Kendricks, a position where the Seahawks are suddenly thin, with Griffin out.

Quarterback Russell Wilson and the bulk of the offensive starters played the first two series, with starters such as receiver Tyler Lockett, running back Chris Carson and left tackle Duane Brown playing after they sat out last week.

Backup QB Paxton Lynch came in for the third series as the Seahawks also replaced Brown, center Justin Britt and right guard D.J. Fluker and began subbing liberally at receiver.

By the fourth series, the Seahawks had replaced their entire offensive line, going with Joey Hunt at center, Jordan Roos and Demetrius Knox at guards and Elijah Nkansah and Marcus Martin at tackles.

SEATTLE'S OFFENSIVE LINE CONTINUES TO TAKE A HIT

Carroll said a lot of the troubles with the offense in the second half started with a banged-up line that resulted in the team going most of the final three quarters with some deep reserves.

The Seahawks entered the game without Mike Iupati, Jordan Simmons, George Fant and Jamarcus Jones, who were all out with injuries. Iupati is a projected starter while Fant is projected to have a regular role as an eligible linemen. Jones and Simmons have good chances to make the roster.

Carroll said Jones practiced Saturday but didn't feel well enough to play Sunday (it's unclear the nature of his injury).

Seattle's depth on the line got worse in the final quarter when Knox left with what Carroll said was a quad/knee injury.

"It's a nasty injury for him," Carroll said. "We don't know what to tell you other than that. Have to do some tests."

Notes

* Running backs J.D. McKissic (foot) and Bo Scarbrough (hand, groin) did not suit up. C.J. Prosise and Travis Homer were in uniform but Prosise did not play. Homer saw his first action with 16 yards on four carries in the second half.

* Tight end Will Dissly, who had not played since suffering a patellar tendon injury last September at Arizona, saw his first action of the preseason.

* Also making his preseason debut was tight end Jacob Hollister, an early standout who suffered an injury in the mock game and sat out against Denver.

* Also among those not playing was receiver Amara Darboh, a third-round pick in 2017 who has yet to play this season.

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