Johnson breezed to victory in the Masters last year, scoring 20 under par, including two stunning 65-shot rounds.
He was five shots clear of joint second-placed Cameron Smith and Sungjae Im.
Ahead of this year’s competition, he said: “My game is in good shape.
“I’m starting to hit a lot of the same shots and getting a lot more comfortable over the golf ball. I feel like it’s in pretty good form.”