Ryu So-Yeon seized the world number one ranking on Sunday as she closed with a two-under 69 at the Northwest Arkansas Championship for her 15th career international title.
Ryu, who won her second major championship in April at the ANA Inspiration, finished the 54-hole LPGA Tour event at 18-under 195 for a two-shot win over South Korean compatriot Amy Yang and Thailand's Moriya Jutanugarn.
"Dreams come true. I always dreamed about it. I cannot believe it," said Ryu. "I didn't expect two good things coming together."
This is the first time in her career that Ryu has reached No. 1, having just slipped past Ariya Jutanugarn, the younger sister of Moriya, when the numbers were calculated on Sunday night.
"First of all, I really appreciate everyone who has been supportive of me, to make me the No. 1 player in the world," she said.
"That's finally made my dream. This is going to be my first week as the No. 1 player in the world. I know it's going to be a lot of pressure and I know I can handle a lot of different things."
Yang fired a seven-under 64 to reach 16-under as she tied Moriya (66) for second place at the Pinnacle Country Club course.
Americans Michelle Wie (64) and Stacy Lewis (69) finished in a tie for fourth while Aussie Lee Min-Jee and Park In-Bee of South Korea both shot 67 to finish at 12-under 201, six shots adrift of Ryu.
Ryu is the first to win twice this season, the previous 15 tournaments having produced 15 different winners.
Ryu had not played since the ShopRight Classic two weeks ago where she missed her first cut in three years. She says the break was just long enough to help her put a series of poor performances to the back of her mind.
"To be honest, today my game wasn't really a great game," said Ryu. "Yesterday my psychologist said 'don't try to be perfect'.
"I had to tell myself 'OK, don't compare this to any other rounds. Just keep focused.'"
The 26-year-old now has five wins on the USLPGA Tour, nine on the Korean tour and one on the Ladies European Tour.
She went into Sunday's final round with a five shot lead but says she didn't feel confident of a victory until she made the putt on 17.
"I made a birdie on 17 then I had a really good walk to 18," she said.
"I was really nervous last night. When you have a five-shot lead everybody is like, you are going to win the tournament for sure, but this is golf. I shot 10 under on Saturday and so that means someone had a chance to shoot 10 under today."
Yang made a Sunday charge after starting her day seven strokes back of Ryu. After the turn, Yang drained back-to-back birdies to pull within two strokes of Ryu but that is as close as she would get.
Moriya eagled 18 to post a bogey-free round and finish a career best tied for second at 16-under par. The finish marks the fourth consecutive top-10 for the Bangkok native who will continue the hunt for her first win on the Tour.
"I get a lot of confidence from this week and hopefully keep playing solid and finish in another good week," the former LPGA rookie of the year in 2013 said.