Day won the WGC-Accenture Match Play Championship in February, but has since been sidelined almost entirely while recovering from the injury.
The Florida Times-Union first reported Day's withdrawal from the field at TPC Sawgrass, noting that he aggravated the injury at the Masters, his only start since his win more than two months ago at Dove Mountain. Day withdrew earlier this season from the WGC-Cadillac Championship and Arnold Palmer Invitational in what were originally seen as precautionary moves, then tied for 20th at Augusta National. He also withdrew from the RBC Heritage the week after the Masters.
Day is No. 6 in the latest world rankings, but according to a PGA Tour statement the 26-year-old is "a few weeks away" from returning to competition. Day becomes the fourth top-50 player to drop out of next week's field, with world No. 1 Tiger Woods recovering from back surgery and Victor Dubuisson (No. 23) and Miguel Angel Jimenez (No. 33) both opting not to enter.