Oakland Raiders wide receiver Antonio Brown lost his grievance case against the NFL on Monday. After the decision, it’s “very unlikely” the 31-year-old All-Pro will appeal the decision, ESPN’s Adam Schefter reports.

Brown, entering his first season as a member of the Raiders after being traded to the Bay Area franchise from the Pittsburgh Steelers in the offseason, raised eyebrows last week when it was reported that his stance against the league’s updated helmets was the true reason behind his absence from fully participating in training camp. Brown was sidelined with a foot injury—also creating whispers that the cause behind the ailment was improper cryotherapy without footwear—but his case against the NFL’s new safety-regulated helmets is apparently stalling him from diving into practice with head coach Jon Gruden’s squad.

Brown is a seven-time Pro Bowler and four-time first-team All-Pro wideout who spent nine seasons with the Steelers. The disgruntled No. 1 receiver was sent to Oakland for 2020 third- and fifth-round picks. Brown has been one of the subjects of the HBO sports docu-series “Hard Knocks,” which is filming behind the scenes at the Raiders’ training camp this August.

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While the 5-foot-10 Brown appears content with his new team on camera, he has yet to practice in full contact with the Silver and Black. He reportedly threatened to retire if he could not wear his favorite “old” helmet.

It’s unclear whether Brown will stay with the Raiders and in the league after losing his grievance case on Monday. However, he did mention earlier in the offseason that he’s “perfectly fine” with walking away from the game while speaking in an interview.