Rory McIlroy has withdrawn from the Arnold Palmer Invitational in Orlando after suffering spasms in his lower back before he was due to start the third round.
The Northern Irishman’s exit was announced by the PGA Tour about 30 minutes before his tee time.
In a later statement, the five-time major winner said: “While warming up in the gym this morning, I felt a small twinge in my back.
“As I started hitting balls on the range before the round, it worsened and developed into muscle spasms in my lower back. Unfortunately, I’m not able to continue and have to withdraw.”
McIlroy held a share of ninth place – nine shots back – after moving to four under on Friday with a round of 68, having shot level par on Thursday.
Having birdied four of the first seven holes on the back nine, McIlroy had said he was “really pleased”, adding he had played a “controlled, patient round of golf”.
The 36-year-old, who was competing in his third PGA Tour event of the season, is due to defend his titles at the Players Championship at Sawgrass next week and the Masters at Augusta from 9-12 April.
A play-off win at the latter against Justin Rose last year saw McIlroy become the sixth man to complete a career Grand Slam, ending an 11-year drought at the sport’s four biggest competitions.
