Attorneys for Richard Sherman plan to file file motions that could further delay the appeal of the Seattle Seahawks cornerback's four-game suspension for a positive test for performance-enhancing drugs, sources say.

Sherman's hearing is scheduled for Friday, but sources say Sherman is convinced he has a strong case and has hired outside legal counsel to go along with the NFL Player Association's.

Sources have told ESPN that Sherman tested positive for Adderall. If the appeals hearing is delayed, Sherman would be available to the Seahawks for even more of the regular season.

Sherman's teammate, fellow cornerback Brandon Browner, decided to drop his appeal last week and starts his four-game suspension for his positive test Sunday.