Rory McIlroy has withdrawn from the Arnold Palmer Invitational just minutes before his scheduled third-round tee time.The reigning Masters champion was set to begin his round at 5:55pm UK time, sitting on -4 after two days of the PGA Tour event.McIlroy has been forced to pull out of the Arnold Palmer InvitationalGettyBut at 5:30pm it was announced that McIlroy would not be taking to the course on Saturday, instead pulling out due to injury.He is stated to have suffered a problem with his back that has forced him to withdraw from a tournament for the first time since 2013.That came during the Honda Classic that year due to toothache.McIlroy arrived at Bay Hill to prepare for his third round action, but that’s when the injury is reported to have occurred. He is reported to have been practising on the range, hitting balls for a couple of minutes, before making the call to pull out.The five-time major winner also gave a thumbs-up to golf journalist Adam Schupak, also telling him he was ‘all good’.McIlroy was nine shots off the lead after his opening two rounds, sitting in the chasing pack on four-under-par.A strong second round that included five birdies brought him into contention of potentially catching leader Daniel Berger.Berger leads the way heading into the weekend, after posting an impressive -13 to boast a strong advantage at the top.At the Arnold Palmer Invitational, there is a total purse of $20million on the line for the world’s best golfers. View Tweet: https://twitter.com/PGATOURComms/status/2030335235020226573?ref_src=twsrc%5Etfw$4million of that will go to the winner, while over $2million goes to the runner-up and £1.4million is taken home for third place.McIlroy will have been hoping to claim a big cut of that, but he will now miss out on any prize after withdrawing.And there are now also concerns over his fitness ahead of the Players Championship and The Masters.Injury worry?McIlroy is the reigning champion at the Players Championship, with the PGA Tour’s flagship event taking place next week.He will be hoping that any injury he suffered will not cause him to struggle or even withdraw from his title defence.Fortunately for him though, it appears his withdrawal from Bay Hill on Saturday was only precautionary. McIlroy will be defending his title at the Players Championship next weekGettyAccording to CBS Sports, the Northern Irishman felt the ‘risk wasn’t worth the reward’ to play through back pain.The Masters are also coming up soon too, with the first major of the golf season scheduled to get going on April 9.McIlroy is also the reigning champion at Augusta after he finally completed the career Grand Slam in 2025.He will certainly not want to have an injury impact his performance when that comes around in a few weeks.