Day said he "couldn't really walk" and has an annular tear in the L4-L5 discs in his back.
Jason Day withdrew from the Arnold Palmer Invitational at Bay Hill after six holes on Thursday, citing a back injury that left him struggling to walk.
“I woke up Sunday and I couldn’t really walk,” Day, ranked No. 11 in the world, told Golf Channel's Will Gray. “Couldn’t sit in a car, it was really difficult. So I ended up coming down here and seeing a physio and trying to do as much work as I possibly could to get ready for this week. It just wasn’t going to work out.”
Day, 31, said an MRI reveled that he has an annular tear in the L4-L5 discs in his back, and that his status for next week's Players Championship—which Day won in 2016—in jeopardy. He said he sustained the injury while practicing last week at that tournament's host venue, TPC Sawgrass.
"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 facet problems as well," Day told PGATour.com. "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.
"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 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 here and (my back) may have loosened up. But, unfortunately, it didn't, so I had to pull out."
He called it quits on Thursday after hitting his second shot into the water on the par-5 16th hole. He was two over par for the day.
This isn't the first time Day has struggled with back issues—he missed the final two FedEx Cup playoff events in 2016 to rehab his back.
Day had gotten off to a nice start in 2019, finishing in the top five in each of his last two starts and posting top-15s in all four of his events this year.
Day is the second top-15 player to withdraw from Bay Hill, as Tiger Woods pulled out Monday with a neck strain.