[size=10pt]Vikings: Depth at linebacker becomes a concern[/size]


They hoped never to face The Question at all, and certainly not in the first month of the season. If one of their starting linebackers were injured, could the Vikings find a suitable replacement among their mostly unknown group of backups?
Yet on Wednesday, the Vikings were addressing that very issue. outside linebacker Ben Leber spent the day in the training room, treating a sprained left knee that has left him questionable for Sunday's game at Buffalo. Leber said, "I don't think it will be a problem" to play, but his absence from practice re-kindled concerns about the Vikings' untested depth at linebacker in an otherwise talent-rich defense.

Veteran Jason Glenn, signed as a special teams player midway through training camp, had been working as Leber's backup. But Wednesday, the Vikings moved third-year player Dontarrious Thomas to the position and gave him most of the work with the first-team defense.

Thomas has never played the "Sam" position (primarily strong side) in the NFL, focusing on the "Will" (weak side) and "Mike" (middle) positions. But he is the only reserve linebacker to see game action on defense this season -- participating in several specialty packages, including goal line -- and is the likely replacement should Leber remain sidelined.

"[The lineup] is not set," Thomas said after practice. "I guess they're just trying to get a feel because I've never played the position before. I'm familiar with the terminology and ... playing Mike, you have to be aware of what all three positions can do. I guess they're just trying to get me some work."

Defensive coordinator Mike Tomlin has stressed flexibility among positions since the team's first minicamp, and the Vikings have given at least three players work at each position. Thomas, Napoleon Harris and Heath Farwell have all practiced at Mike. Thomas, Farwell and E.J. Henderson have worked at Will, while Leber, Glenn and now Thomas have spent time at Sam.

Marquis Cooper, who has been inactive since the Vikings claimed him on waivers Sept. 5 from Tampa Bay, was moved Wednesday from Sam to Will.

"You have to be able to play all three positions," Glenn said. "Just a slight motion can make a Sam into a Will and a Will into a Sam. We all try to learn each other's positions so that we can jump in if we have to."

Glenn arrived in Minnesota only after first-round pick Chad Greenway tore the anterior cruciate ligament in his left knee Aug. 14. Greenway almost certainly would have been the team's top backup at both outside positions, but on Wednesday he could do nothing more than stand idly in the locker room, chatting about Iowa football and providing updates on his rehabilitation.

Greenway's injury left the Vikings with only one backup, Thomas, who had started more than one NFL game; Glenn made one start for the New York Jets in 2003. Glenn, Cooper and Farwell exclusively have been special-teams players in their careers, but "all those guys are looking for is an opportunity," coach Brad Childress said.

"They're high-level special teams performers," Childress said. "And all they're looking for is an opportunity to get on that field, to get on tape, and show their wares."

Thomas should get that first crack, whether it is this week or the next time the Vikings have a hobbled starter. A second-round draft choice in 2004, Thomas always has teased coaches with his athletic ability and raw speed; Tomlin, in fact, initially penciled in Thomas as his starting Mike linebacker until swapping him with Harris during a May minicamp.

Mental mistakes cost him a starting job in both 2004 and '05, but Thomas said the similarity between positions in Tomlin's scheme has helped him reduce those errors.

"Sam and Will are pretty much vice versa," he said. "If you know Will, and you know what to do at that position, you pretty much know what to do if you're on the other side. That helps you out."

Leber hopes to test out the knee today in practice, and the Vikings should have a clearer picture of his condition by Friday. Then the Vikings will know, for sure, if it's time to answer The Question