Rejuvenated Australian golfer Jason Day has set himself a target of reaching world number one in the next five years following his brilliant season on the U.S. PGA Tour, a far cry from his struggles to get out of bed earlier this year when plagued by mental demons and illness.

The 23-year-old confirmed his rich potential with his debut Tour win at the Byron Nelson Championship in May last year and cemented his place among the elite with two runner-up finishes at the U.S. Masters and the U.S. Open this year.

In between, however, was an angst-filled period as he battled sinus problems and a dip in form that left him sapped of energy and bored with practice.

Enter Neale Smith, an Australian coach based in California, who taught Day to enjoy his homework and have a clearer focus on his game-plan during tournaments since being hired in February.

It (was) very hard to get up in the morning and go, 'You know what, I want to go play golf', Day told reporters on a conference call on Thursday.

I wasn't playing great golf. I was very disappointed, down on myself on the golf course. I'd go, 'I don't want to be here.' I'd go home for a week or two weeks. I'd be bored. I'd go out and practice. It wasn't fun.

I'd go back out and play. That was even more disappointing. It was kind of like a vicious cycle of me losing to myself.

That's why I employed a mental coach ... It worked out great for me.

I'm loving the game a lot. It's just fun where I am right now. I'm very, very blessed to be where I am right now.

Day's rise to world number seven has made him the first pick in Greg Norman's Internationals team for next month's Presidents Cup against the United States in Melbourne.

Despite his citizenship, Texas resident Day has scarcely any more knowledge of the Royal Melbourne Golf Course than his opponents, and the November 17-20 Presidents Cup will be only his second professional tournament in his home country.

Widely anointed Australia's next major champion, Day can nonetheless expect a rock star reception on his return home as a young gun on a team stacked with more seasoned compatriots.

I just hope we can kind of get something going and we can win, said Day, who was born in Beaudesert, a country town outside of Brisbane.

Right now I'm not worried about how good I'm going to look or how fun it's going to be. I really want to play well for the team. I just don't want to let my teammates down. I think that's the main thing.

Day's steady rise in his five years since turning professional has been overshadowed by illnesses that have baffled doctors and the side-effects of drugs to treat them, and the golfer still takes a measured approach to his preparations.

He had not picked up a club for the past month, but spent the time working out in the gym as he strives to become an all-round athlete in the vein of his childhood hero Tiger Woods.

Woods has been battling to get back into form as he tries to rebuild his swing and his private life following the breakup of his marriage in the wake of revelations about his infidelities at the end of 2009.

But Day said he had his fingers crossed for a pairing with the former world number one when the two tee off at the Australian Open in Sydney, the week before the Presidents Cup.

I've talked to my agent about it, he said. I wouldn't put it past him if they paired me with Tiger. I know it would be very, very fun. There would be a lot of people out there, no doubt.