Phil Mickelson's scores from Doral over the past two years clearly suggested that the redesigned Blue Monster wasn't completely to his liking.

He had to re-learn a course that he played for more than 20 years, and indicated Thursday that he finally has the new Doral figured out.

Mickelson shot a 5-under 67 on Thursday in the opening round of the Cadillac Championship, the first World Golf Championships event of the year. Seeking his first win since the British Open in 2013, Mickelson made seven birdies and finished the day one shot back of leaders Scott Piercy and Marcus Fraser.

Fraser had seven birdies before his lone bogey of the day, and Piercy also got to 7 under at one point before settling for his 66.

Danny Willett, Adam Scott, Jason Dufner and Charley Hoffman were all two shots back of Piercy, each carding 68s. World No. 1 Jordan Spieth was in a group another shot back, three off the pace at 3 under, and said that even on a relatively calm day by Doral weather standards, it felt like a grind.

Spieth was in a featured group, with world No. 2 Jason Day and No. 3 Rory McIlroy with him. McIlroy shot 1 under, Day finished at even par.

Bubba Watson was part of a three way tie for eighth at three-under par. Rickie Fowler was tied for eleventh at two-under.

Defending champion Dustin Johnson shot an even-par 72, putting him in a tie for 28th.