Martin Blake, Golf Australia

Jason Day has acknowledged the gravity of his back injury, telling media in Hawaii on the eve of his return to tournament golf that he may need to shorten his swing as a precaution.

Although Day still believes the thumb injury that bothered him in 2014 was more serious – career-threatening, in fact – than the disc and ligament issues that forced him to withdraw from the game for three full months, he said that he would need to continue monitoring the damage in his lower back.

Some observers believe that Day’s violent golf swing, repeated time after time and year after year, is a recipe for a back injury, but the Australian said he was on top of it.

“I know exactly what’s going on there,” the world No.1 told a media conference before the SBS Tournament of Champions at Kapalua Resort, which starts on Friday, Australian time. “Every year we get an MRI at the end of the year, a DEXA (dual energy x-ray absorptiometry) scan at the end of the year, all these scans to make sure we had a baseline before.

“With the L4 and L5 disc there’s actually more space there. Usually when you have degeneration of a disc it slowly gets worse and worse. For some reason mine’s got better, I’ve got more space in between the disc so it’s actually good, it’s just the facet joint locks up.”

Day said he felt good after some serious rehabilitation of his back and core which included work to balance the strength on his left side. He believes that tens of thousands of shots hit on the range and on the course right-handed inevitably lead to an imbalance that needed to be corrected.

But he said the thumb injury that troubled him in 2014 was the most scary injury he has endured. “I actually thought I was going to have to quit the game. I literally couldn’t hold the club, and obviously you’ve got to hold the club.

“You can get away with a back a little bit every now and then. You can kind of get through it. I was more concerning to me because it (the thumb) was new, and when something’s new, you don’t know how long it’ll take.”

Day, who tees it up from 9.40am Friday (AEST) with three other Australians (Aaron Baddeley, Greg Chalmers, Rod Pampling), remains “addicted to the process of trying to get better”, and has set himself some new targets.

Having held on to the top world ranking at year’s end, he wants to retain it for an extended period. “The biggest thing for me is obviously it’s great to see you finish at No.1, but I’d like to go a full year, not just half a year and finish at No.1. I’d like to go a full year and slowly build on that.”

Kapalua fits his eye; he closed with an equal course record 62 in 2015. “If I could guarantee my spot here every year I’d come back every single year because I just love it,” said Day.