Lydia Ko became the youngest world number one of all time in either of the women's or men's game on Saturday, despite surrendering her lead at the Coates Golf Championship to Choi Na-yeon.
The 17-year-old led heading into the final day in Ocala, Florida, but could not seal her momentous achievement with a win at the season-opening event.
After posting a final-round 71, Ko finish tied for second alongside American Jessica Korda and Korean Jang Ha-na at 15 under, one shot short of the lead, with a double bogey at the 17th hole effectively costing her victory.
Choi of South Korea lifted the trophy following her four-under-par 68 at the Golden Ocala Golf and Equestrian Club.
The New Zealander, nevertheless, climbs above Inbee Park to top the women's rankings.
At 17 years, nine months and seven days, Ko easy eclipses the previous mark in women's golf set by South Korean Jiyai Shin, who was 22 years and five days in 2008.
Ko also surpasses American 14-time major winner Tiger Woods, who set the men's record at the age of 21 years, five months and 15 days in 1997.