Kevin Williams' knee ligaments OK

EDEN PRAIRIE, Minn. -- Minnesota Vikings defensive tackle Kevin Williams suffered a hyperextended knee, bone bruise and postular capsular strain after a low block from San Francisco 49ers offensive tackle Joe Looney on Sunday night. But an MRI showed the six-time Pro Bowler avoided any ligament damage to his right knee.

Williams walked off the field under his own power after the block from Looney, which led teammate Jared Allen to call the play dirty during a TV interview. Williams said he was unhappy that Looney – a second-year tackle – went low on him, but told reporters he could not say if the play was improper until he watched it on video.

The Vikings registered a complaint with the league claiming the unpenalized hit was illegal, but on Monday the NFL determined Looney's hit was legal and did not violate the new rule on peel-back blocks.

The 32-year-old Williams, who is in the final year of his contract, was likely to sit out the Vikings' preseason finale against the Tennessee Titans on Thursday night anyway. Now, he will try to return in time for the regular season opener on Sept. 8 against Detroit, and the Vikings could use him. They are also without rookie defensive tackle Sharrif Floyd, who had a minor knee operation after being sufferinga low block in the Vikings' first preseason game, until the start of the regular season, and defensive tackle Christian Ballard is away from the team for personal reasons.

ESPN senior NFL analyst Chris Mortensen contributed to this report.