Oakland Raiders to discipline star Antonio Brown after he threatened to hit GM Mike Mayock (VIDEO)

Oakland Raiders wide receiver Antonio Brown threatened to hit GM Mike Mayock in the face during an angry confrontation between the pair, according to reports from the United States.

After being issued with fines totaling $53,950 for no-showing for team sessions, Brown posted a copy of his fine letter to his Instagram story with the message: “WHEN YOUR OWN TEAM WANT TO HATE BUT THERE’S NO STOPPING ME NOW DEVIL IS A LIE. EVERYONE GOT TO PAY THIS YEAR SO WE CLEAR.”

It appears things aren't as clear as he believed, as Mayock and Brown subsequently became involved in a confrontation described by NFL Network reporter Ian Rapaport as a shouting match, with Mayock not doing very much of the shouting. That row reportedly ended with Brown threatening to hit Mayock in the face before punting a football and telling him to fine him for that.

Mayock later appeared in front of the press, but gave no details of the incident, simply saying: “Short and sweet, Antonio Brown is not in the building today. He won't be practicing. I don't have any more information for you right now. When I have some and it becomes appropriate, you guys will all get it but that's it for today.”

It left reporters and fans alike to speculate on what might happen next, with Brown certain to be disciplined, but the extent of that discipline yet to be confirmed.

Brown has been constantly in the headlines throughout the off-season after his ill-tempered departure from Pittsburgh Steelers and subsequent arrival at the Raiders.

Many believed GM Mike Mayock and head coach John Gruden had picked up the best receiver in the league, but his reputation for being a high-maintenance star led some to question whether his move would be a success.

Those doubts only grew after he suffered an unfortunate foot issue after cryotherapy, then refused to practise after the NFL ruled that his chosen brand of helmet was no longer cleared for use in the league.

His highly-publicised holdout over his helmet issue led to a lucrative helmet deal, and now, after his training ground outburst, things appear to have gone even further downhill for the controversial receiver.