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Jason Day used to think no one could beat him, and there wasn't much evidence to prove him wrong.

When he won The Players Championship last year against the strongest field in golf — he was the first wire-to-wire winner at the TPC Sawgrass in 33 years — it was his seventh victory in 10 months. He was No. 1 in the world with a points average only Tiger Woods had reached over the last two decades. He was determined to do more.

"Winning is never enough," he said that day. "And I've got to try and do it as much as I can before my time is over."

Hard as it is to believe now, that was his last victory.

Day makes it sound as though the burden of being No. 1 became too much to bear, which led to him slowly rappelling down the mountain with surprisingly few chances of doing what for the longest time had felt so easy.

He threw away a good chance to win at the Bridgestone Invitational when he lost the lead on the back nine by missing the last six greens in regulation. He fell too far behind Jimmy Walker to catch him in the PGA Championship. And then an old nemesis — back pain — returned during the FedEx Cup playoffs, and the 29-year-old Australian withdrew during the last two tournaments.

Day effectively reached what he refers to as "base camp" in February when Dustin Johnson replaced him at No. 1.

And now it's time to start the climb.

It's a tall order.

Getting to the top might prove to be easier than getting back.

"Dustin Johnson is out there playing pretty well," Day said Tuesday. "That usually makes it pretty hard when someone hits it 350 yards down the middle and flicks it on with a wedge and holes all the putts. That's what I was doing a couple years ago."

Johnson makes the task look like Everest. Coming off three straight victories against the three toughest fields of the year, he missed the Masters following a slip down the stairs that bruised his back, went six weeks without playing and returned to finish one shot behind last week in North Carolina. Not only is Johnson at No. 1, his lead is greater than anyone's except what Woods enjoyed over the last 20 years.

Day, whose goal in January was to stay at No. 1 the entire year, is now No. 3.

"Being able to climb that mountain is very difficult, because sitting back and knowing that I've done it before, how much work I actually had to put into it, is tough in itself," Day said. "Because you're sitting there going: 'Man, that's all I think about is golf ... and getting to No. 1 in the world.' Saying all that is great, but if you don't have the desire to get there, then there's no use. You won't get there at all."

Day said he lost his desire when he lost his No. 1 ranking after 47 straight weeks, and it wasn't just golf.

He was deeply troubled at the start of the year when his mother was diagnosed with lung cancer and doctors in Australia offered a bleak outlook. A few months later, Day brought her to Ohio for more tests. She had the tumor removed and is doing so well that Day said she is back home, and even returned to work.

"Finally, I can kind of take a breath and sit back and go, 'OK, I need to start my trip back up the mountain again,'" Day said.

Getting to No. 1 was his life's ambition. That might explain why Day, unlike previous players who reached No. 1, speaks so openly about the pressure and demands.

Adam Scott enjoyed his 11 weeks at No. 1 in 2014, although Scott comes from a different generation. Scott played when Woods was at his best and wasn't sure he could ever get there. He added Colonial to his schedule when he reached No. 1 just to savor the feeling of showing up at the course as the world's best player (he won that week).

For Rory McIlroy, it was a matter of finding the next mountain to climb, which Jack Nicklaus and Woods did so well.

"I think it takes just as much hard work to stay there as it does to get all the way up," McIlroy said. "And it's golf. It's life. There's going to be ebbs and flows in everyone's careers, and you just have to accept that and realize that there's going to be some times when it isn't quite what you want and it's not going your way."

His longest stay at No. 1 was 54 weeks — only Woods, Greg Norman and Nick Faldo have had longer stretches (Woods holds the record at 281 weeks from 2005-10).

McIlroy has always said that when the game is good, it's hard to remember ever playing badly. And when the game is bad, playing great seems like a distant memory.

The mountain looks as high as ever for Day because it's been awhile since he was playing great.

And because he's trying to catch someone who is.