The reigning US Open champion fell at his rented home Wednesday afternoon, about 23 hours before his scheduled start in the final group at the year's first major golf championship, according to his agent.
Johnson, an oddsmakers favorite to claim the champion's green jacket after winning his past three starts, was expected to visit the PGA Tour's medical trailer Thursday morning for possible X-rays or an MRI exam.
While the 32-year-old American was icing the injury and hopeful of being able to play, Johnson's setback could remove a major threat from the list of contenders among the field of 94.
Four-time major champion Rory McIlroy, the world number two from Northern Ireland, hopes to complete a career grand slam with a victory while third-ranked Jason Day is trying to overcome a light practice schedule after taking time off to be with his mother as she underwent lung cancer surgery.
Five-time major winner Phil Mickelson would become the oldest Masters champion just two months shy of his 47th birthday while 2015 Masters and US Open winner Jordan Spieth tries to bounce back after a Sunday back-nine meltdown cost him last year's crown.
Players will tee off onto a rain-soaked course from overnight thunderstorms in cold and windy conditions with gusts above 20 mph (32 kph) playing havoc with the world's greatest shotmakers for the first two days of the 72-hole showdown.
"It's going to be pretty tough -- 20-30 mph winds is not what we're used to around here," Day said. "And it's going to be cold, so the ball is not going to be flying very far. Typically, I kind of like those tough conditions. I'm a grinder in that sense. I need to respect it more and not really be too aggressive."
Spieth says strategy will take time
"It's going to take a good five six holes, I think, before we really understand what this golf course is going to give us," he said.
Winds also could cause chaos on the lightning-fast and undulating Masters greens, pushing putts off-line.
"You don't want to have 5-footers from above the hole when the wind is blowing," Spieth said. "They become a less than 50-50 chance from five feet with the wind blowing. Because of the speed of the greens and the amount of slope there is, the wind affects the ball that much more."
Some relish difficult conditions
"The weather is going to come in and that's going to magnify the misses for a lot of players," Mickelson said.
"If you're in the right spot, you can take advantage of your short game and salvage a lot of pars, and I hope to rely on that knowledge and skill to keep myself in it heading into the weekend.
"And if you put it in the wrong spot, you'll end up making bogeys and doubles."
McIlroy ready to challenge
"It has been quite blustery here the last few years. We've experienced those conditions and hopefully I know how to handle them by now," McIlroy said.
"It's a course that can tempt you into doing a little bit too much. It's just a matter of being smart, taking your medicine when you have to and moving on."
Golf icons Jack Nicklaus and Gary Player will make their ceremonial opening tee shots for the first time without the company of fellow legend Arnold Palmer, a four-time Masters champion who died last September at age 87.
"Tomorrow will no doubt be an emotional goodbye, but at the same time, an even more powerful thank you to the man we dearly love," Augusta National chairman Billy Payne said.
Every spectator Thursday will be presented with a commemorative "Arnie's Army" badge.