PHOENIX — She ended Yani Tseng's 109-week run at No. 1, and joined Cristie Kerr as the only Americans to top the rankings that began in 2006. Kerr was No. 1 for five weeks over three stints in 2010.
"It's crazy," Lewis said. "That was my goal kind of since the middle of last year and I really didn't think it would be possible this quick. ... I'm going to have fun, I know that. I watched Yani struggle with it for too long and I'm going to go have fun."
Lewis beat Ai Miyazato by three strokes, closing with an 8-under 64 to finish with a tournament-record 23-under 265 total on the cactus-lined Wildfire layout. Miyazato, three strokes ahead with six holes to play, finished with a 71.
The tournament turned with a three-stroke swing on the 16th hole, a day after Lewis was penalized two strokes for her caddie's blunder on the short par 4.
On Sunday, Lewis took a two-stroke lead with a birdie after Miyazato made a double bogey following an errant approach shot that left her with an unplayable lie in a desert bush.
Miyazato took a four-stroke lead over Lewis and Jee Young Lee into the final round when Lewis was penalized after play Saturday when it was ruled caddie Travis Wilson tested the sand before Lewis played out of a bunker on No. 16.
"I wasn't even mad at him because he didn't do anything on purpose," Lewis said. "I just felt really bad for him just because all the stories were, `Stacy Lewis' caddie, Stacy Lewis' caddie.' The spotlight was on him and he never wants that. We were so motivated today."
Miyazato was a stroke ahead on the 16th tee and seemingly in perfect position in the fairway on the 307-yard hole. But the straight-hitting Japanese star's pitching wedge sailed left, hit on the bank near the edge of the green and rolled into the desert bush.