EDEN PRAIRIE, Minn. (AP) The Minnesota Vikings have placed center John Sullivan on injured reserve with a designation to return, because of a bad back.

The move was made Thursday, four days before the season opener at San Francisco.

The Vikings announced that Sullivan had surgery Wednesday. He underwent a lumbar microdisectomy, a procedure typically done to address a herniated disc. Sullivan hadn't practiced since Aug. 18. Joe Berger has replaced him in the starting lineup.

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Teams can place one player per season on short-term injured reserve with the designation to return. Sullivan will be eligible to return to practice after six weeks and to games after eight weeks. Factoring in Minnesota's bye, Sullivan must miss the first seven games.

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