His decision to withdraw from Houston, where he finished third in 2016, means he will arrive at the year's first major as the clear favourite.
Johnson never trailed in any of his seven matches at the Austin Country Club where he capped a dominant week with a 1-up victory over Spain's Jon Rahm.
At Augusta National, reigning U.S. Open champion Johnson will be seeking the second major title of his career.
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(Reporting by Frank Pingue in Toronto. Editing by Steve Keating.)
