Adrian Peterson could be out long-term after opting for knee surgery

Minnesota Vikings running back Adrian Peterson could miss the majority of the regular season as he needs surgery to repair his torn meniscus.

The Vikings are not putting a timescale on Peterson's absence and have not yet opted to place him on injured reserve, which could become an option after he goes under the knife on Thursday.

Coach Mike Zimmer confirmed on Wednesday that Jerick McKinnon would take Peterson's starting role and the Vikings have also signed former Denver Broncos running back Ronnie Hillman.

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Peterson, 31, had struggled to break through the Tennesee and Green Bay defences in his first two games of the season and was hurt late in the week two win over the Packers.

"Everything is possible," Zimmer said. "Could be season-ending, could be three weeks, four weeks. Who knows?

"We're not the type of team that's going to sit back and cry."

The Vikings lost starting quarterback Teddy Bridgewater to a season-ending knee injury before the season even started and placed tackle Matt Kalil on injured reserve on Wednesday.

Hillman could eventually work himself into a regular role on the Vikings offence after leading the Broncos in rushing yardage last season with 863. 

He was released by the Broncos after they re-signed CJ Anderson and drafted Devontae Booker early in the 2016 NFL Draft.

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