Antonio Brown left training camp on Sunday over his anger being denied use of his helmet.

Mike Mayock issued an ultimatum to Brown in the process.

"You all know that AB is not here today, right?" Mayock told a group of beat reporters as practice began Sunday afternoon. "So, here's the bottom line -- he's upset about the helmet issue. We have supported that, we appreciate that. But at this point, we've pretty much exhausted all avenues of relief.

"So, from our perspective, it's time for him to be all-in or all-out, OK? So, we're hoping he's back soon. We've got 89 guys busting their tails, we are really excited about where this franchise is going and we hope AB's going to be a big part of it, starting Week 1 against Denver. End of story. No questions, OK? Just wanted you guys to know where we were. Fair?"

Brown has also been upset with the league not allowing him to wear his Schutt Air Advantage helmet.

The Raiders were excited about Brown's return and after he was a full participant in Saturday morning's walk-through, the team anticipated him practicing fully as soon as Sunday.