WE knew Jason Day was tough, but in a tell-all interview the recent world No.1-ranked golfer revealed how he suffered ongoing abuse at the hands of his later father Alvin.

Day’s story has become widely publicised during his five-win US PGA Tour season. Especially after his maiden Major victory in August, the Queenslander didn’t refrain from admitting his family’s poverty growing up in Beaudesert, Queensland.

Or how he developed a drinking problem at the age of 12 after his father’s death.

But the 27-year-old told GOLF magazine (US) how he feared playing bad golf as a child and facing a subsequent “beating.”

“I remember once shooting a (poor) score, and he (Alvin) goes, ‘You’re going to get it in the parking lot’,” Day told GOLF writer Cameron Morfit.

“So I get in the car. I’m scared. We drive out of the club, he stops on the side of the road. He just starts whaling on me with both hands, closed-fist punching. I was 11. I had bruises all over me. But I mean, it is what it is.”

The US PGA Champion won more than $US 9 million on the course alone this year, but told AAP it wasn’t money that motivated him to play well as a kid.

“It’s a weird situation,” Day told AAP.

“If I played bad golf my dad would belt the crap out of me.

“I was so scared of playing bad golf because I would get a hiding but I guess that’s what made me play so well.

“But then to have a loving person such as Col, and have him raise me from 12, his influence has been immeasurable. I owe him more than I could put into words.”