SEATTLE – When the locker room doors opened Sunday, the Seattle Seahawks' hexed backfield had vanished. MVP running back Shaun Alexander's locker was neatly tucked, a pristine monument to a broken foot that could sideline him for another week or two. And standing around a corner, quarterback Matt Hasselbeck balanced on a pair of crutches, limping from a right knee injury that could prove season-altering.

A league source said Sunday night Hasselbeck has been diagnosed with a sprained MCL and is expected to miss "a couple of weeks," pending the outcome of an MRI on Monday. Unless tests dictate otherwise, the Seahawks will be without their Pro Bowl backfield next week against Kansas City – and perhaps far longer.

"Fair don't have [expletive] to do with football," said tight end Jerramy Stevens, who just finished playing his first game of the campaign after offseason knee (left) surgery. "It sucks that a couple of our premier players got hurt. Mo's [Maurice Morris] been stepping up for Shaun, and Seneca Wallace is going to have to step up for Matt however long he's out. It's part of the game."

That part of the game suddenly has taken an extreme toll on the Seahawks, who fell 31-13 to the Minnesota Vikings at Qwest Field. Now Seattle must await word on the extent of Hasselbeck's injury, which occurred early in the third quarter when Vikings linebacker E.J. Henderson slipped off a block and hit Hasselbeck's lower right leg. The quarterback's leg already had planted for a pass, and the blow looked remarkably similar to the one suffered by Cincinnati's Carson Palmer in last season's playoff game against the Steelers. As a result of his injury, Palmer had surgery and underwent six months of rehab.

"Those things happen," Seahawks coach Mike Holmgren said of Hasselbeck's injury. "You talk to your team, and you prepare a team for the possibility you might not have your starting quarterback. You better have some resiliency because there are a lot of games left to play."

"I'm not nervous. I think if we have to play without Matt, it would probably change some things, yeah. But I'm not nervous about it. Seneca's a good player. With a week of practice under his belt … he's expected to go in and play the position well."

And he'll have to for the Seahawks to remain in playoff contention. While Seattle still is situated in first place in the NFC West – tied at 4-2 with St. Louis and having beaten the Rams last week – it can't afford prolonged struggles. While the NFC's playoff scenarios are far from being figured, it's not hard to see the writing on the wall. Beyond the four divisional winners, there could be as many as six teams fighting for two wild-card spots.

The Seahawks do have the benefit of playing one of the softer schedules down the stretch (six games remaining against teams that have one or two wins), but there is no telling how the team would respond if Hasselbeck were to miss an extended period. Getting Alexander back should be a boost, but there's no guaranteeing the soreness in his foot won't linger or that he'll be able to get the running game into gear with the offensive line still struggling from a lack of continuity.

Much like the injury at the running back spot, Hasselbeck's loss likely will be a significant adjustment for Seattle's offense. The offensive line has yet to settle into a groove since the departure of Steve Hutchinson (now with the Vikings) and looks out of sync with Morris, who is more of a slasher than a patient, north-south runner like Alexander. Now add in Wallace, whose mobility in the pocket is sure to be another adjustment for a line accustomed to a pocket quarterback.

However, that's not a concern shared by at least one lineman.

"It might be real tough on the defense we're going to face next week," center Robbie Tobeck said. "Matt's a great quarterback, but Seneca is a different guy and does different things. And we might do some different things."

Any lost time for Hasselbeck would create some chaos with the receivers, too, considering the rapport he was beginning to develop with Deion Branch and the rhythm he was establishing with Darrell Jackson over Hasselbeck's last six quarters (seven catches for 188 yards and two touchdowns). Despite being versed in the offense, it's hard to envision Wallace stepping in without some issues, considering he has zero starts under his belt and 27 regular-season pass attempts in the last three-plus years.

Regardless of what happens with the offense, the unit isn't Seattle's only problem. The defense is having issues of its own – specifically giving up big plays. While linebacker Julian Peterson has given the defense a boost and the linebackers have been solid, the unit missed a crucial cutback by Minnesota running back Chester Taylor, which led to a 95-yard touchdown. Not an overly powerful back, Taylor ground out only three yards per attempt on his other 25 carries, but the late third-quarter score, which came cutting off a Hutchinson block, gave Minnesota a deflating 24-10 lead.

Add Taylor's run to the 67-yard touchdown catch by St. Louis wide receiver Torry Holt last week, and 40- and 46-yard catches by Chicago's Bernard Berrian (one for a touchdown) Oct. 1, and the defense is beginning to look like an overaggressive unit prone to exposure. Whether it's biting on play action or overpursuing in running lanes, the mistakes have been a consistent thorn in Holmgren's side.

"The long plays are killing us," defensive tackle Rocky Bernard said. "The games before, we've given up a few long plays. … It's something we're struggling with this year, and it's something we can definitely work on."

"The bottom line is, we've got a lot to accomplish," linebacker Julian Peterson said. "We need to go out there and prepare for Seneca Wallace being the quarterback and whatever happens with Matt happens. The defense has to take care of what's going on there, and the offense has to rally around Seneca. It's not where we thought we would be at this point in the season, thinking about all these different things. But it's where we are. This is reality."