Brown attended a team meeting just one day after general manager Mike Mayock said it was time for him to be "all in or all out."
Raiders wide receiver Antonio Brown rejoined the team for on Monday amid the ongoing helmet dispute that has plagued his offseason, ESPN's Adam Schefter reported.
According to Schefter, Brown was present at the Raiders' facility despite the walk-through practice being canceled for the day. Brown's appearance comes just one day after he decided to skip practice.
On Sunday, Raiders general manager Mike Mayock issued a statement on Brown's absence.
"At this point, we've pretty much exhausted all avenues of relief," Mayock said. "So from our perspective, it's time for him to be all in or all out."
New NFL rules being enforced this season require players to wear helmets that are certified by the National Operating Committee for Standards and Athletic Equipment (NOCSAE). Players who fail to wear approved helmets will be disciplined, per the league.
The old helmet that Brown wore during his career with the Steelers is no longer certified by NOCSAE and therefore fails to meet the standards of the NFL's policy. Brown filed a helmet grievance with the NFL but lost.
Brown was traded to the Raiders on March 13 after a tumultuous 2018 season with the Steelers. He has caught 100-plus passes in each of the past six seasons and was a four-time All-Pro with the Steelers.
The Raiders finished last year at 4–12 and fourth in the AFC West.