Patrick Reed's caddie Kessler Karain confirmed he was in an altercation with a fan at the Presidents Cup on Saturday.
Reed's forgettable campaign at Royal Melbourne Golf Club, where he arrived amid cheating allegations, continued following a third consecutive defeat alongside United States team-mate Webb Simpson.
Booed and heckled throughout the 13th Presidents Cup following his antics at the Hero World Challenge, 2018 Masters champion Reed went down 5 and 3 to International pair Hideki Matsuyama and C.T. Pan in the morning's four-ball.
And it led to a clash between Reed's caddie and a supporter prior to Saturday's foursomes.
"As a caddie, one of your jobs is to protect your player," Karain said in a statement to Fore Play.
"We have been known for having fun with some good banter, but after hearing several fans in Australia for three days some had taken it too far. I had had enough.
"Riding on the cart, guy was about three feet from Patrick and said, 'you f****** suck'. I got off the cart and shoved him, said a couple things, probably a few expletives.
"Security came and I got back in cart and left. I don't think there's one caddie I know that could blame me.
"Unless his bones break like Mr.Glass, the most harm done was a little spilled beer, which I'm more than happy to reimburse him for."
Reed has been public enemy number one after his two-stroke penalty during last week's Hero World Challenge in the Bahamas.
Already a maligned figure on the PGA Tour, American golfer Reed was penalised for improving his lie in the bunker, hitting the sand twice during his practice swings, sparking controversy and claims of cheating.
Booed on day one, Reed taunted the Melbourne crowd on Friday by mimicking a shovelling motion amid heckles.