Atthaya Thitikul, 19, is the new World No. 1, becoming just the second teenager to ever reach the top ranking, after Lydia Ko did so in 2015. Thitikul, Ko and Tiger Woods are the only golfers, male or female, to reach World No. 1 before age 22.
Although she's a rookie, Thitikul made her presence known when she won the JTBC Classic in March. She finished in the top 10 seven more times before winning again in September at the Walmart NW Arkansas Championship. In her next three events, she finished in the top 10 each time, most recently finishing sixth at the BMW Ladies Championship.
A week after the BMW, the Rolex Women's Rankings were recalculated and Thitikul rose above Jin Young Ko, unseating her as the No. 1 player in the world. Ko also played the BMW Ladies Championship, but withdrew due to injury.