World No. 1 Dustin Johnson withdrew from the Masters on Thursday afternoon right before his group was slated to tee off.
According to ESPN.com's Jason Sobel, Johnson walked off the first tee and back toward the clubhouse following a short session on the practice range.
Johnson was forced to withdraw after he suffered a back injury Wednesday as the result of a fall on the staircase at his rental home in Augusta, Georgia.
"He landed very hard on his lower back and is now resting, although quite uncomfortably," Johnson's manager David Winkle said Wednesday, per ESPN.com news services.
Johnson later told ESPN's Tom Rinaldi he would "give it a try" following his warmup, as ESPN.com's Bob Harig reported Thursday afternoon, but he evidently wasn't close to full strength.
"I can't swing full," he said after withdrawing, per Sobel. "I can't make my normal swing and I didn't think there was any chance I could compete."
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