The World No 1 Dustin Johnson has been forced to withdraw from the Masters are suffering a lower back injury in a fall down some stairs.

Johnson headed into the tournament as one of the favourites having won his last three starts, but did not take a shot at the first major championship of the year.

The American arrived at Augusta National around mid-day and warmed up under the watchful eye of swing coach Butch Harmon.

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He was determined to tee off at the first but was in clear discomfort as he completed his warm-up, grimacing as he took a few practice swings. He was also unable to bend over to tee up his ball.

Despite his clear discomfort Johnson walked over to the first tee with Bubba Watson and Jimmy Walker but decided to return to the clubhouse after a few more painful practice swings.

Johnson talks to Augusta National member Fred Ridley (2nd R) (Getty)

“I want to play,” Johnson told reporters after leaving the first tee. “I just can't swing.

“It sucks because I am playing the best golf of my career. This is one of my favorite tournaments of the year.

“Then a freak accident happened (Wednesday) when I got back from the course. It sucks. It sucks really bad."

“I was doing everything I would to try to play. Last night, it was ice, heat, ice. I was up pretty much all night trying to get it ready for today. I had it worked on all morning.

“Obviously, I can make some swings. But I can't make my normal swing.”

The World No 1 was in clear discomfort while completing his warm up (Getty)

Harmon meanwhile told reporters that Johnson experienced pain down his left side while completing his warm up, necessitating his withdrawal.

“He has pain in his left side, he started to warm up, but his eight irons were going only 100 yards,” he told Sky Sports.

“He had to make a swing through the ball, then he felt it and went off for some more physio.

“He said 'I have to make some full swings'. The driver was the key, if he could make full swings with the driver then felt he felt he could get round. But he said the practice swings hurt more that then real thing.

“He said 'I'll have to give it a try and if it doesn't happen then I'll come off.”

Jimmy Walker and Bubba Watson will play without Johnson (Getty)

Johnson was injured late Wednesday afternoon when he took what his agent described as a "serious" fall down a staircase, in a rented property near the course.

“It would have been better if it was full set of stairs,” Johnson said of his injury.

“I would have slid all the way down. But there were only three steps. I landed on my left side. My left elbow is sore and bruised. My lower left back took the brunt of it.”

This is only the second time in the history of the Masters that the world number one has not played at Augusta, after Tiger Woods withdrew from the 2014 tournament.