South Korea-born New Zealander Lydia Ko became the youngest world number one in golf history by reaching the top of the women's rankings aged 17.
Ko secured the number one ranking by finishing in a tie for second at the LPGA Coates Championship in Florida.
She eclipses Tiger Woods, who was 21 when he became men's world number one in 1997.
"It's amazing," said Ko. "It's a huge honour to be in that ranking. All I was focused on was trying to play my best."
South Korean Jiyai Shin had been the youngest player to top the women's rankings, doing so aged 22 in 2010.
Ko took her record despite surrendering a four-stroke overnight lead in the opening LPGA event of the season, which was won by South Korean Na-Yeon Choi.
But she still gained enough ranking points to move past South Korea's Inbee Park in the rankings.
Ko became the youngest winner of an LPGA Tour event with victory in the Canadian Women's Open in August 2012 at the age of 15.
She turned professional in October 2013 and has won five times on the LPGA Tour and once on the European Tour.
"I'm just going to just focus on my golf, not think about the rankings," she said. "The rankings always come after the results."