EAST LAKE • The closing in of Dustin Johnson on the summit of golf's world ranking may be the least of Jason Day's worries.

As the Australian world No. 1 departed East Lake on Friday, a back injury having curtailed his Tour Championship appearance, the narrative was ominously familiar.

Fitness woes, and all manner of them, have been a constant companion to Day's professional career.

With this in mind, it seems partly remarkable he has scaled such heights; either Day has a penchant for overdramatisation or he recovers especially well.

Johnson, who is in the form of his life, has Day's No. 1 status firmly in his sights to the point where it would be a surprise if the American does not assume that position in the near future.

Where issues of the back are concerned, Day must be extra careful. The troubles of his close friend Tiger Woods provide all necessary evidence of that.

Day and Woods have at least one thing in common - a powerful but borderline violent golf swing which will place inevitable pressure on their back.

"It's not what you want to be happening in your career and it's clear that there is something going on in Jason's back and that's why he's treating it with caution," said Day's compatriot Adam Scott.

"The thing is that a back issue can be serious for any golfer. Hopefully, Jason gets on top of it quick.

"But it also shows that if you play a punishing schedule and if you are carrying any sort of injury through the season, it's very difficult. "

Day had a bulging disc in his back which appeared to remedy itself.

The current injury has been diagnosed as a strained ligament in his lower back.

"It's not the first time that it's happened," said Day.

"I put the tee in the ground at the BMW Championship and my back went out. Last time it went out, I (had) changed a diaper.

"So it's nothing where I go and physically make a move at it during a swing and my back goes out. It literally is from the smallest things: picking up a pillow, picking up something off the ground or just moving the wrong way.

"Fortunately for me, the disc has actually come back in. It's like you've got to do the small exercises. It's like brushing your teeth every morning. I just have to do them because it's part of my daily routine now."

THE GUARDIAN