CLEVELAND (AP) Lydia Ko, who earned an exemption to join the U.S. LPGA Tour in October as a 16-year-old, has signed with management company IMG.

Born in South Korea and raised in New Zealand, Ko is already No. 4 in the women's world rankings and won the Swinging Skirts World Ladies Masters last week in her second start as a professional.

She won the Women's Canadian Open at 15 last year to become the youngest winner in tour history, and defended that title this year.

Paula Creamer and Michelle Wie are among the women's golfers represented by IMG.

Guy Kinnings, global head of golf at IMG, says in a statement released on Thursday that Ko "is an incredibly impressive young lady and an astonishing player."