Jeju - Major-winner Jason Day on Wednesday said he was targeting getting back to world No 1 after his mother's cancer scare had left him not wanting "to be on the golf course".
"My mum getting lung cancer was very difficult," the Australian told reporters ahead of the US PGA Tour's CJ Cup, which begins in South Korea on Thursday.
"I don't have any grandparents. I don't have my dad. I don't have anyone. If I lost my mum all I would have would be my two sisters," said the world No 9 on Jeju Island.
"So realising how much she sacrificed for me growing up it meant a lot to me to be there for her. And I didn't want to be on the golf course.
"I knew that if she was going to die then I wanted to spend as much time as I could with her," he said, his voice cracking with emotion. "Because I only get to see her once a year.
"Fortunately the surgery (in March this year) went well and now I'm able to focus back on golf."
After making his major championship breakthrough by winning the 2015 US PGA Championship, the 29-year-old went on a hot streak to rise to the top of the world.
Day was still No 1 at the start of 2017 but with his last win coming a year and a half ago at the Players Championship his ranking has tumbled.
He missed the cut at the US Open and finished outside the top 20 in the Masters and the British Open.
Day has shown glimpses of form since, finishing ninth place in the US PGA Championship in August and recording two top 10s since.
"It was a little bit of a combination of things why I had this poor season. I was a little bit burnt out from 2016 and 2015," said Day.
"I didn't know how to handle being No 1. Next time I get there again I will handle it a little bit differently," said Day, who has not been outside the world's top 10 since the end of the 2013 season.
"I still worked very hard to get through that burnt-out stage. And then my mum got lung cancer.
"Hopefully the distractions that I've had on the golf course and off the golf course have gone away and I can focus on climbing back to No 1."
Ten of the world's top 30 will tee off on Jeju Island, south of the mainland, in the second event of a three-week swing as the US PGA Tour spreads its wings further into Asia.
World No 4 and US PGA Champion Justin Thomas is the top-ranked player at the par-72 Nine Bridges course for an event which carries a first prize of $1.665 million as part of a massive $9.25 million purse.