RANCHO MIRAGE (California) • Lydia Ko's world No. 1 status is under threat. But the New Zealand golfer says she will try not to think about rankings when she defends her title this week at the LPGA's ANA Inspiration, the first Major championship of the year.

Thailand's Ariya Jutanugarn and South Korean Chun In Gee both have the top spot in their sights heading into the tournament at Rancho Mirage, California.

Ariya has been ranked second to Ko for 35 weeks in a row.

While the 19-year-old Ko has managed three top-10 finishes since making wholesale changes to her support team before the start of the season, she missed the cut in her title defence at the Kia Classic in Carlsbad, California, last week.

"There is pressure because you're the No. 1 ranked player - you should play awesome week in and week out, try and win every week," she said of the stress of maintaining the position she has held for 75 consecutive weeks.

"If that was the case I would love it. But you know, almost if you're second every week, I think you'd probably be the No. 1 ranked player anyway... it's more about consistency and how many times you can put yourself in contention and then sometimes being able to pull it off."

Her missed cut in Carlsbad, which she said came down to a baulky putter, was just the second of her pro career. But she insisted she would not let it drag her down.

"I'm just going to try and erase last week," she said. "I'm just going to think last week was just an off-week and just move on."

With her ANA Inspiration victory last year, Ko became the youngest two-time Major champion in LPGA Tour history. She had become the youngest golfer, male or female. to win a Major title in the modern era at the Evian tournament the previous September.

She sealed the victory with a two-foot birdie putt after a brilliant approach shot on the final hole, beating Chun and England's Charley Hull by one stroke.

"You know, the real special thing is walking down across that bridge and seeing all the different names of these great legends that have walked this path and also jumped in Poppy's Pond and won this championship," said Ko. "The great thing about this event is that there is so much history behind it."

Ariya was in prime position to capture her first LPGA win at one of the Tour's most revered venues last year, but she bogeyed her final three holes to finish fourth, two strokes behind Ko.

She rebounded with a vengeance, stringing together three victories last May and winning back-to-back titles later in the year that included the Women's British Open.

The Thai snatched LPGA Player of the Year honours from Ko, even though she has not yet been able to nudge the teenager from the top of the rankings. Ariya said this year that her disappointment at Rancho Mirage was the key to what proved to be a remarkable season.

"I learnt a lot, especially the last three holes," she said. "Last year, I just kept hitting the ball and tried to do the same thing even though I was nervous. I learnt that when I get nervous, I have to do something different."

Ko knows the lesson has made Ariya an even more dangerous rival.

"Ariya played so well last year," she said. "Obviously it wasn't the greatest end to the ANA, but she won a lot after that. She just played consistently well. She's going to continue to keep playing well and go for those trophies."

AGENCE FRANCE-PRESSE

LPGA ANA INSPIRATION

Day 1: Singtel TV Ch115 & StarHub Ch209, 11.59pm