Von Miller has been told that he could be suspended for the first six games of the 2013 NFL season, according to a report.
ESPN has said that the Denver Broncos linebacker is facing a longer ban than initially reported for breaching the league's substance-abuse policy.
The NFL Players Association has stated that the 24-year-old has not tested positive for a performance-enhancing drug, although league rules do allow punishment for missing tests or counselling sessions.
A source from the players union has told NFL.com that Miller is trying to negotiate a four-game absence.