The NFL Players Association released a statement late in the afternoon saying the veteran guard filed a non-injury grievance.
"The grievance challenges his suspension for conduct which was alleged to have occurred while he was with the club," the union's statement said. "In the grievance, Incognito requests that the hearing be held on an expedited basis so that he can immediately resume playing for the team.
"The NFL Players Association will continue to protect the rights of all players."
Incognito was suspended by Miami on Nov. 3 for misconduct related to the treatment of teammate Jonathan Martin, who abruptly left the Dolphins late last month to receive help for emotional issues.
The NFL is investigating whether Incognito harassed or bullied Martin. Incognito has said the conduct was all part of the normal locker room environment.
ESPN first reported the grievance.
Incognito has missed one game, and the suspension by the team can last for four games. The Dolphins, who have not said how long Incognito is suspended, said they do not comment on grievances.
Martin is scheduled to meet Friday with Ted Wells, the independent investigator hired by the NFL. Dolphins owner Stephen Ross also plans to meet with Martin.
A second-year pro, Martin left the team because of what his attorney has alleged was daily harassment by teammates, including Incognito.
On Monday, Ross announced the formation of two committees to examine the Dolphins' locker room culture. In recent days, players have been virtually unanimous in saying it doesn't need to be changed.
The case has inspired a national debate about workplace bullying.
AP Sports Writer Steven Wine contributed to this story.
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