WATCH: Phil Mickelson hits back at his critics after he deliberately stopped his ball rolling off green at US Open
Phil Mickelson told his critics to "toughen up" after admitting he deliberately hit a moving ball to gain an advantage in the third round of the US Open.
Mickelson, who was already four over par for the day on his 48th birthday, badly overhit a putt on the 13th green which looked in danger of rolling off the putting surface.
The five-time major winner prevented that from happening by running after the ball and hitting it while it was still rolling, a breach of rule 14-5 which incurs a two-shot penalty.
Former US PGA champion Steve Elkington called for Mickelson to be disqualified, writing on Twitter: "Absolutely 100% conduct unbecoming ... hes trying to embarrass the @USGA DQ his ass."
uhh, you can't do that phil mickelson pic.twitter.com/R5zwQV9GqJ— Jordan Heck (@JordanHeckFF) June 16, 2018
However, Mickelson, who eventually made a 10 on the 13th in a round of 81 which equalled his highest score in the US Open, said: "If someone is offended I apologise, but toughen up.
"Knowing the rules is never a bad thing. You always want to use them in your favour. I know the rules and the ball was going to go off in a bad spot. I did not feel like continuing going back and forth. I would still be out there potentially.
"I've wanted to do it many times before and finally did. I should have done it a couple of times on 15 at Augusta. That would have saved me a shot or two back then."
Mickelson and playing partner Andrew Johnston were laughing about the incident as they walked off the green and Mickelson added: "How can you not laugh? It's funny. I just wanted to get to the next hole and did not see that happening without the two shots."
Commentating on the incident for Fox, former Ryder Cup captain Paul Azinger said: "That's the most out of character I have ever seen Phil. I think he just snapped. I'm sure he is going to regret that."
And two-time US Open champion Curtis Strange added: "He will feel some embarrassment because there are a lot of people and kids watching that really admire this guy."
Commentating on the incident for Fox, former Ryder Cup captain Paul Azinger said: "That's the most out of character I have ever seen Phil.
"I think he just snapped. I'm sure he is going to regret that."
The incident on Mickelson's 48th birthday brought to mind a similar episode by John Daly at the 1999 U.S. Open at Pinehurst No. 2.
Daly, however, already had a reputation for being wild and unpredictable, whereas Mickelson's reputation as American golf's golden man has been cultivated over nearly three decades of exemplary behavior on the course.
It was not immediately clear what was Mickelson's motive in striking the ball.
Whatever it was, the Fox television analysts were stunned.
"John Daly's reputation took a hit after what he did at Pinehurst in '99 and I fear it will be the same for Phil," said former U.S. Golf Association executive director David Fay.