The Vikings on Thursday placed starting center John Sullivan on the Injured Reserve/Designated for Return list after the veteran had a procedure on his back.
He cannot return until Week 9.
Sullivan hasn't practiced since Aug. 18 and missed Tuesday's practice because of back spasms. He is expected to be replaced in Monday night's season opener at San Francisco by veteran guard Joe Berger.
"I think (Berger) will do well if he has to go," said offensive coordinator Norv Turner said Tuesday.
The Vikings said in a statement that Sullivan underwent a lumbar microdiscectomy on Wednesday.