Jason Day’s breakthrough major win at the PGA Championship was a milestone of perseverance.

It was a triumph of hard work and discipline and the professional apex of a life that could have – and, for a while, did – spiral dangerously out of control.

Day’s father Alvin, who gave him his first golf club, died when he was just 12, and the youngster handled the pain by drinking himself into oblivion.

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He was boozing heavily, and his mother, Dening, feared he would self-destruct.

Jason Day competing on the Nationwide Tour in 2007. Photo: Getty

So she made a sacrifice, stepping in to save him from himself. She took out a second mortgage on her home and sent him to boarding school.

“It was very easy to stop partying because there was nothing else to do except go to school and golf,” Day said in 2011.

“There was literally nothing around us.

“So I was pretty much forced to go to school and golf.

“And I realised what my mum had done.”

Day began practicing more than 30 hours a week, and after school he moved to America – Mecca for an aspiring young golfer.

At 19, he became the youngest man to win on the NationWide Tour – the PGA Tour’s second-tier.

It was at that event that his romance with Ellie Harvey, a 21-year-old aspiring beautician, started to bloom.

Day had first met Harvey when she was 19, at the pub – Mavis Winkle’s Irish Pub, in Twinsburg – in which she worked at night.

It took him a year to work up the guts to approach her (honing the same nerves of steel he showed in his final round on Sunday).

Day was agonisingly close to a play-off at the British Open. Photo: Getty

She drove to see him compete at the Legend Financial Group Classic.

Ellie watched Day’s final round, and he won.

Six months later they moved in together, despite reservations from Ellie’s dad.

“I had my dad hat on and cautioned her,” Tom Harvey said.

“Strike one, he’s a jock. Strike two, he’s a professional. And strike three, he’s from Australia.

“I exaggerated it as much as I could, but (Ellie) blew her old man off. I told her to go in with eyes wide open.”

Ellie and Jason wed in 2009, and they hit the road across America in a massive RV, as Jason began to carve a name for himself in the most competitive golf tour in the world.

The couple have a three-year-old son, Dash, and are expecting another child.

He was committed to his sport. Golf saved him.

His win in the PGA Championship was just reward for continually putting himself in contention over the past five years.

There were tears when Day finally elevated himself among the major winners. Photo: Getty

Prior to his breakthrough win, Day had nine top-10 finishes in the past 20 majors. Most recently, he missed out on the play-off for the British Open by just one shot.

So when he tapped in for a final-round 69 at Whistling Straits – and a score of 20 under, breaking Tiger Woods’ major record of 19 under – the tears flowed freely.

This was a triumph hard-earned, for a kid who could have so easily gone off the rails.

Jason Day has some hard miles on his clock.

He lost eight members of his family when Typhoon Haiyan lashed the Philippines in 2013.

He was introduced to golf by his father, and his absence left a hole that almost consumed him.

Dening Day said golf was the game that saved her son.

“He was drinking and listening to his peers instead of his parent,” she told News Corp.

“But, he was committed to his sport. Golf saved him.”

Alvin Day wanted his ashes scattered at Augusta, although the club said Jason had to wait until he was world No.1 to do so.

He may not have long to wait. And, no doubt, Alvin will be up there smiling while he waits.

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