Keegan Bradley, the first player to win a major using a belly putter at last year's PGA Championship, was accused of being a cheater by a fan as he played the final hole in Sunday's third round at the World Challenge at Sherwood Country Club.
The United States Golf Association slammed the outburst at the 18-player event hosted by Tiger Woods as an "unfounded criticism from an obviously uneducated spectator", calling it "a deplorable incident" with no place in their game.
The ban on belly putters won't come into effect until 2016 at the earliest, and for the next three months both the Royal and Ancient and the USGA will be seeking feedback on the proposal.
The USGA says it remains entirely within the rules of golf for players to anchor the club while making a stroke and there should not be a shred of criticism of such players or any qualification or doubt about their achievements, and it is inappropriate even to suggest anything to the contrary.
Bradley has been among several players under the spotlight since last week's proposal by golf's rulemakers to ban putters being anchored to a player's chest, stomach or chin.
