Australian major winner Steve Elkington has unleashed a social media tirade at Phil Mickelson after the American caused US Open controversy by striking a moving golf ball during a bizarre meltdown.
Elkington joined a chorus of former players and fans calling for five-time major winner Mickelson to be disqualified from the Shinnecock Hills spectacle in New York.
Mickelson chased after his travelling ball on the 13th green on day three and struck it before it could roll farther from the hole, breaching rule 14.5 which prohibits a player from hitting a moving ball.
The 48-year-old, who has a record six runner-up finishes at the US Open, was assessed a two-stroke penalty by organiser the USGA and given a 10 for the hole.
He signed for an 11-over-par 81 and a 17-over total.
Mickelson tried to downplay the controversy and offered a limp apology to reporters after signing his scorecard.
"If someone is offended, I apologise but toughen up," Mickelson said.
Playing with England golfer Andrew Johnston, Mickelson was seen laughing on the broadcast.
"How can you not laugh; it's funny," Mickelson said.
However, 1995 US PGA Championship winner Elkington believes the USGA should have disqualified Mickelson, likely for a serious breach of rule 1-2, which states "a player must not take an action with the intent to influence the movement of a ball in play".
"Absolutely 100% conduct unbecoming ... hes (sic) trying to embarrass the (at)USGA DQ his ass," Elkington wrote in a series of Twitter posts.
"Not sure what's more stunning!! Phil running down a putt & hitting it while its moving or giving the thumbs up & s*** eating grin on the next hole...WTF was that?"
Former European Tour player Tony Johnstone wrote: "How can the USGA NOT kick his butt out of there?"
Added two-time US Open champion Curtis Strange: "I've never seen anything like that from a world class player in my life."
Mickelson said he knew the ruling was in his favour when he struck the ball, which could have left him a near impossible pitch shot.
"Oh, no question; it was going to go down in the same spot behind the bunker and I wasn't going to have a shot," he said.
"I know it's a two-shot penalty hitting a moving ball; it's my understanding of the rules.
"I've had multiple times where I've wanted to do that. I just finally did."