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Dustin Johnson will not compete in this year's Masters Tournament.
On Wednesday night, before the first round, Johnson injured his back falling down stairs at a house he rented in Augusta, Georgia.
On Thursday, Johnson decided to give the tournament a shot. However, he left the first hole before taking a single shot and officially withdrew from the tournament.
Here is the moment Johnson walked off the course, via ESPN:
There were some troubling signs leading up to Johnson's tee time.
ESPN's Tom Rinaldi reported early Thursday that Johnson was in "significant pain" and had a hard time finding a position to rest comfortably.
Johnson's trainer told Golf Digest that Johnson had only recently gained mobility.
"He was up and moving around and definitely going in the right direction," Joey Diovisalvi said. "He was very much in an under-control point going to bed last night."
According to ESPN's Jason Sobel, Johnson is the second player ranked No. 1 in the world to miss the Masters. The first was Tiger Woods in 2014.
This is a developing story.