McIlroy retained the title at the DP World Tour’s Dubai Desert Classic in January, a week after finishing second at the Dubai Invitational, but he has been outside the top 20 in his four PGA Tour events over the past six weeks.
However, his ball striking for the most part on the first day at Sawgrass was impeccable as he made a brilliant start by birdieing his first three holes.
Three more birdies followed over his next five holes, including a deuce at Sawgrass’s signature 17th hole after a superb tee shot to the sixth foot.
That left him three clear, but his first visit of the day to the water after his tee shot on 18 meant he did well to drop a shot after a full three-wood to the front edge of the green .
McIlroy got back to six under by birdieing the par-five second and made two more shots by sinking putts of 10 and 15 feet at the fourth and sixth.
Then came his accident in the seventh after another drive into the water, leading to lengthy discussions with his playing partners about the location of the penalty after McIlroy had already taken it.
A rules official ultimately supported McIlroy’s judgment, but after failing to find the green with his third shot, following the penalty he was unable to get up and down.
However, McIlroy showed determination by sinking a 15-foot birdie putt at the final par five to join Schauffele on seven under.