Robinson relishes chance to play

Adrian Peterson, like most Vikings starters, probably won't play in Thursday's preseason finale against Houston. Toby Gerhart, still slowed by a sore ankle and Achilles' tendon, probably won't play either. Ditto for Lorenzo Booker, who has a sore back.

That means a lot of opportunity for a few running backs hoping to grab a final roster spot.

One of those is Alexander Robinson. A Twin Cities native, Robinson went to at De La Salle High School before a productive career at Iowa State. Signed as a free agent, he has only seven carries over the first three preseason games.

He's looking forward to getting more work Thursday.

"I think the coaches want to take a chance to evaluate other players on the squad," he said after Tuesday's practice. "You have to look at that as an opportunity show what you can do."

Vikings offensive coordinator Bill Musgrave said Robinson and Tristan Davis would get the bulk of the work against the Texans. Recently signed free agent Caleb King also might get a look, too.

Musgrave said Robinson has progressed well throughout camp.

It would appear difficult for any of the three to garner a roster spot. But that could change if, for example, Booker's injury proved serious enough that he could miss significant time.

Splitting timeTuesday was a busy day for Everson Griffen. A day after he was moved from defensive end to linebacker -- at least on an experimental basis -- he struggled at times during a drill that tests linebackers' lateral movement. Still, defensive coordinator Fred Pagac was intrigued with Griffen as a stand-up player and said Griffen could split his playing time Thursday between the two positions.

"He's a very good athlete," Pagac said. "Before it's all said and done, he's going to be a good defensive end. He might end up being a heck of a linebacker, too. We wanted to check his movement from behind the ball."

Pagac said the move was not a comment on Erin Henderson's performance at outside linebacker. It was more of a search for the 53 best players.

Brinkley to IR?A source confirmed the Vikings were deciding whether to place backup middle linebacker Jasper Brinkley on season-ending injured reserve late Tuesday night. An announcement is expected as early as Wednesday morning.

Etc.• Once again, the Vikings are entering a preseason game having not decided if Jamarca Sanford or Tyrell Johnson will be the starting strong safety.

"These guys have been fighting all camp," Pagac said. "I think both have done an excellent job. ... We are going to make a decision after this game."

• Offensive lineman Chris DeGeare (concussion), tight end Visanthe Shiancoe (hamstring), Booker (back) and cornerbacks Asher Allen (toe), Devon Torrence (quadriceps) and Chris Cook (hamstring) didn't practice. None will play Thursday.