UPDATED 8/25, 1:20 p.m. ET: Antonio Brown will officially have to change helmets.

On Sunday, Pro Football Talk's Mike Florio reported that AB's second grievance against the NFL was rejected. As a result, the wide receiver will not be able to wear his preferred Schutt Air Advantage helmet.

He now has to figure out his next move, after he claimed that he wouldn't play if he wasn't allowed to wear the helmet. 

See original story below.

Oakland Raiders star wide receiver Antonio Brown has filed another grievance against the NFL in his ongoing fight to wear the now discontinued Schutt AiR Advantage helmet that he wore during his time with the Pittsburgh Steelers, NFL Media’s Ian Rapoport reports.

Brown argues that the NFL should allow players to be given a one-year grace period to phase out an older model helmet. The problem with AB's latest defense is that the helmet he wants to wear is no longer certified by the National Operating Committee for Standards and Athletic Equipment, and league policy dictates that a player cannot wear a helmet that doesn't meet this requirement. 

The NFL also forbids players from wearing a helmet older than 10 years, and the 10-year-old Schutt AiR Advantage helmet falls into that category. 

Brown previously threatened to never play football again if he couldn't wear his old helmet, but appeared to back off his threat after an arbitrator ruled against him. 

On Sunday, Raiders general manager Mike Mayock appeared to reach his breaking point with Brown, publicly calling for him to either be "all in or all out" with the 2019 season drawing near.