Only 17, top-ranked Lydia Ko says she's already planning to retire from golf by the time she's 30, and become a psychologist.

Ko makes her second start at No. 1 in Thursday's first round of the Women's Australian Open at Royal Melbourne along with Karrie Webb and Australia's Su Oh, who won the Australian Ladies Masters last week in her second start as a professional.

The South Korean-born Ko says she will soon start an on-line psychology degree to prepare for life after golf.

"I say my plan is to retire when I'm 30 so I'm not just going to go to the beach and hang out for the rest of my life," Ko said Wednesday.

"There's always a second career that comes along with it and I'm trying to build up towards it and, because I'm playing a sport, psychology links well with it."

Ko finished second in the LPGA's 2015 tour opener in Florida on Jan. 31 to become the youngest player of either gender to become world No. 1, breaking the record set by Tiger Woods by almost four years.

Ko, who moved to New Zealand from South Korea when she was six, travels from her Florida base with her mother, Tina. Her older sister, Sura, has an architecture degree.

"My mom will get me off my iPad and phone and tell me to work hard and look at the text books," Ko said.

In her second year as a pro, Ko said she wasn't putting too much pressure on herself to win a major this year.

"Last year I had two top-10 finishes (in majors) which was better than the year before when I had one," Ko said. "I'm looking for more consistency in playing majors and then one day that will give me a chance to be around the lead."

Webb won the Women's Open at Victoria Golf Club in Melbourne last year for her record fifth title. South Korea's Chella Choi was second, a stroke back.

Also playing on the Royal Melbourne composite course are South Korean players Na Yeon Choi, who beat Ko in the season opener, and So Yeon Ryu and Kyu Jung Baek, and No. 4-ranked Shanshan Feng of China.