Washington Redskins running back Adrian Peterson has a grade 1 high ankle sprain and a grade 2 low ankle sprain, according to ESPN.
He also told reporter Josina Anderson that "I'm good" to play Thursday night at the Minnesota Vikings, where he launched his career and ran for 11,747 yards in 10 seasons, starting in 2007. He reiterated his prognosis to NFL Network's Tom Pelissero, saying his ankle was "night and day from yesterday. I should (be) ready to go."
Peterson suffered the injury in the third quarter of Sunday's 9-0 loss to the San Francisco 49ers. He underwent an MRI exam Monday to determine the extent of the injury.
With Derrius Guice (torn meniscus) on injured reserve and Chris Thompson (turf toe) missing last week's game, the Redskins have a thin backfield, with Wendell Smallwood (13 carries, 58 yards this season) the only other running back on the roster.
The 34-year-old Peterson has 83 carries for 307 yards and a touchdown this season, his second with Washington, which is 1-6 and 30th in the league in scoring at 12.9 points per game.