The Vikings leading tackler, LB Erin Henderson, may not be able to go Sunday against the 49ers. He sat out of practice Thursday with a concussion that wasn’t know about until Wednesday.

“There were no indications [of a concussion] after the game or Monday or Tuesday,” said coach Leslie Frazier. “And then Wednesday he came after practice and just didn’t feel right, so that’s when they decided to take him through protocol for concussions.”

Frazier said the training staff took Henderson some tests on Thursday and he would go through more after practice to determine if he can work at practice on Friday. The plan if he can’t play on Sunday is for LB Marvin Mitchell to start in his place, MLB Jasper Brinkley to stay in on nickel coverage for Henderson and Mitchell to come out.

DC Alan Williams has confidence in Mitchell to be able to handle the starting role:

“Marvin has been in ball games as a starter, he’s been in ball games as a backup, he’s played a lot of football so everything that happens is not new to him out there,” said Williams. “That gives me comfort and when he’s been in ball games, he’s performed well.”

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