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Running Back Adrian Peterson #28 Of The Minnesota Vikings Is Getty Images

LANDOVER, MD - DECEMBER 24: Running back Adrian Peterson #28 of the Minnesota Vikings is helped off the field after being injured in the third quarter against the Washington Redskins at FedEx Field on December 24, 2011 in Landover, Maryland. (Photo by Patrick Smith/Getty Images)

Vikings star running back injured

Adrian Peterson likely tore the ACL in his left knee during the Vikings' win over the Redskins, sources told Yahoo! Sports.