ORLANDO, Fla. -- Back issues forced Jason Day to withdraw from the Arnold Palmer Invitational on Thursday after just six holes of the opening round.
Day told the PGA Tour that he had an MRI on Monday that revealed he has a tear in a disk in his lower back.
Day, 31, a 12-time PGA Tour winner who won the Arnold Palmer tournament at Bay Hill in 2016, had not played since tying for fourth at the AT&T Pebble Beach National Pro-Am last month and told the PGA Tour that his back had been bothering him over the past week.
"My back was sore when I was practicing from Tuesday to Saturday, and I was going to practice on Sunday, but I woke up and couldn't really walk or sit in the car,'' said Day, who has a history of back issues. "I was on a dose pack to try and get the inflammation out of it and that didn't get any better.
"I saw a physio here and tried to do as much work as I possibly could to get ready for this week. I couldn't play at 100 percent today, so I just wanted to see if I could get out there and it may have loosened up. But unfortunately it didn't, so I had to pull out.''
The Australian, who is ranked 11th in the world, had back issues that forced him to withdraw from the BMW Championship and the Tour Championship in consecutive weeks at the end of 2016.
Day said he hoped to be ready to play next week's Players Championship, which he won in 2016. He had five top-15 finishes in five starts this season.