Dustin Johnson, in 5th start since his leave, smashes way to victory at Doral

Dustin Johnson looks at his shot from the rough off the 18th fairway as heavy rain falls during the third round of the Cadillac Championship golf tournament Saturday, March 7, 2015, in Doral, Fla. (AP Photo/Wilfredo Lee) (The Associated Press)

J B Holmes hits from a sand trap on the second fairway during the final round of the Cadillac Championship golf tournament Sunday, March 8, 2015, in Doral, Fla. (AP Photo/Wilfredo Lee) (The Associated Press)

DORAL, Fla. – A month after he returned from his curious leave of absence, Dustin Johnson was posing with another trophy.

In a power show Sunday on the Blue Monster at Doral, Johnson was flawless on the back nine and closed with a 3-under 69 to win the Cadillac Championship for his second World Golf Championship.

Johnson took advantage of a collapse by J.B. Holmes, who lost a five-shot lead and closed with a 75 to finish one shot behind. Masters champion Bubba Watson made three bogeys on the back nine and shot 71 to finish two shots behind.

Johnson won for the ninth time in his PGA Tour career.

He returned from a six-month break last month to seek help for what he described as personal challenges.