World No1 Dustin Johnson was forced to withdraw from the Masters just minutes before his tee time after failing to overcome injury.
Johnson, who has won his last three starts, suffered a serious fall on a staircase on Wednesday evening to throw doubt over his participation in the competition.
He was going outside to move a car when he slipped on wooden steps in his rental home and landed on his lower back and both elbows.
Johnson, who had won his previous three events, said: "It sucks. I want to play. I'm playing the best golf of my life and to have a freak accident happen yesterday afternoon, it sucks really bad.
"I have been worked on all morning and obviously I can take some swings, but I can't swing full, I can't make my normal swing and I didn't think there was any chance I could compete."
Johnson said that the accident happened when he was heading outside to move his car before his son Tatum got back from daycare.
"I was wearing socks and slipped and went down the three stairs," he added. "The left side of my lower back took the brunt of it and my left elbow is bruised as well."
The favourite for the green jacket was advised by doctors to remain stable and take anti-inflammatory medication and began hitting balls at 12:50 local time on Thursday.
His tee time in the first round of the 81st Masters was scheduled for 2:03pm local time, though weather was causing delays, and withdrew at around 2.10pm.
With updates throughout the morning, Johnson's condition went from unknown to "cautiously optimistic" of participation in the late morning.
Johnson was set to compete in his eighth Masters, having finished T4 on -1. Bubba Watson and Jimmy Walker teed off without him.