An injured Jason Day didn't show up at Bay Hill for practice rounds on Tuesday or Wednesday prior to the Arnold Palmer Invitational in Florida.
On Thursday, the former World No.1 cast significant doubt over whether he will contest next week's Players Championship by withdrawing from the Palmer event just six holes in – citing a back injury.
Day was two-over-par at the time and visibly struggling with his swing.
He walked off Bay Hill's par-5 16th hole – his seventh – and revealed an MRI scan he underwent Monday indicated an annular tear in the L4/L5 disc.
The 2016 winner of the Palmer event believes he aggravated his back during intense practice last week at TPC Sawgrass – site of next week's elite Players Championship.
"I (aggravated) it last Sunday, and then got an MRI Monday which came back that I had an annular tear in my disc and then I've got 'set problems' as well," Day said.
"My back was sore when I was practising from Tuesday to Saturday (last week) and I was going to practise on Sunday, but I woke up and couldn't really walk or sit in the car.
RIGHT: Day has withdrawn from Bay Hill with a back injury, having aggravated it while practicing at TPC Sawgrass last week. PHOTO: Sam Greenwood/Getty Images.
"I was on a dose pack to try get the inflammation out of it and that didn't get any better.
"I saw a physio here (in Orlando) and tried to do as much work as I possibly could to get ready for (Bay Hill).
"I couldn't play at 100 percent today so I just wanted to see if I could get out here and see if my back loosened up at all. Unfortunately it didn't."
Day was still confident he will be able to play the Players Championship at TPC Sawgrass next week, which is regarded as golf's unofficial fifth major.
The 31-year-old equalled the course record 63 at Sawgrass during his four-shot win there in 2016.
"I think it's just rest I need, to be honest, and hopefully I'll be ready next week," Day said.
Day has history of injuries, notably when he had to withdraw from the 2012 Masters during the second round at Augusta National with a strained left ankle.
He also withdrew mid-tournament from the final two events of the 2016 PGA Tour play-offs with a strained ligament in his lower back.
In 2014 a thumb injury sidelined Day for nearly two months forced him to skip the Players Championship.
- Evin Priest, Australian Associated Press