Phil Mickelson believes that a ban on players using long putters would be "grossly unfair".
Golf's ruling bodies - the Royal and Ancient Club and United States Golf Association - are considering forbidding the use of putters that can be anchored to the body.
With a decision expected soon, Mickelson has urged the authorities not to outlaw the increasingly-popular belly and broomhandle putters.
"I understand both sides, it's just that I don't think you can take away what you've allowed players to use, practise and play with for 30 years," Mickelson said ahead of the Barclays Singapore Open. "I think it is grossly unfair.
"I also understand that it's a better way to putt and all young players should start to putt that way as they get older. It's a more efficient way to putt.
"I am concerned about some amateur players that use it and I don't want to deter people from the game of golf."
Tiger Woods has claimed that the putter should be the shortest club in the bag, but Open runner-up Adam Scott disagrees.
"I'm not necessarily sure his views on what the putter should be are correct at all," said the Australian, who has prospered on the greens since switching to a broomhandle putter.
"I don't think the putter should be the shortest club in the bag. That has never been a rule in golf, so I don't know why it should be now."
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