ORLANDO - New Zealand teen star Lydia Ko became golf's youngest-ever world number one Saturday even though she only settled for a share of second at the season-opening LPGA Coates Championship.
The South Korean-born prodigy took the top spot at 17 years, nine months and seven days.
"It's a big honour to be the world number one," Ko said. "To have that honour by my name, I can't believe it."
Ko eclipsed the age marks of South Korean Shin Ji-Yai, who was the youngest prior women's world number one at age 22 in 2010, and US star Tiger Woods, who was 21 when he ascended to number one for the first time in 1997.
"Tiger Woods, he's amazing," Ko said. "I just try to have fun out there and I just came into the ranking. I'll just try to keep focused and not worry about the ranking and learn from this season."
Ko squandered a four-stroke lead and struggled on the final holes to help South Korean Choi Na-Yeon capture the title on 16-under par 272 with Ko, American Jessica Korda and South Korean Jang Ha-Na sharing second on 273.
Despite a double bogey at 17 and a struggle just to close with a par, Ko did just enough to overtake Park In-Bee for the top ranking after the South Korean shared 13th on 284.
"When I heard the news I kind of went, 'Really?' and made a face," Ko said. "It was tough finishing with the last two holes like that."
Ko fired a 71 Saturday while Choi fired a 68 in the final round, staged a day earlier than usual to avoid a last-day conflict with American football's Super Bowl.
"I played so well for so long," Choi said. "I was really nervous."
It was another taste of history for Ko, who won the 2012 and 2013 LPGA Canadian Women's Open titles as an amateur, the first of those at age 15 making her the youngest winner in LPGA history.
That success prompted Ko to turn professional and the LPGA to allow Ko to join the tour in 2014, when she won three titles, was named LPGA Rookie of the Year and captured the season-ending Tour Championship and the season points prize for a record $1.5 million payday last November.
Choi fights back to win
Ko began the final round with a one-stroke lead and opened with back-to-back birdies to seize a four-stroke lead on the field.
Choi answered the challenge and took her first victory since 2012.
Choi birdied three holes in a row starting at the third. While Ko birdied the par-5 fifth hole but took a bogey at the eighth, Choi birdied the par-5 seventh but closed her front nine with a bogey.
Choi birdied the par-5 12th and another birdie at the 14th put her on 17-under, one stroke ahead of Ko, who missed an eight-foot birdie putt at 14 and settled for her sixth par in a row.
Ko responded with a birdie putt from halfway across the green at the par-3 15th, raising her right fist in celebration with a look of surprise on her face after watching the ball roll in.
When Choi missed a three-footer for par, Ko was alone in the lead at 17-under with two holes to play.
At the 17th, Ko found a bunker and sent her second shot into the trees, then chipped into the fairway.
Her fourth shot rolled off the front right edge of the green. She chipped 15 feet shy of the cup but hit a tension-packed putt for double bogey and only fell to 15-under, one back of leader Choi as they walked to the par-5 18th tee.
Choi put her approach 20 feet past the pin while Ko was in rough left of the green, then chipped over the green and into a bunker and blasted out two feet from the cup.
Ko tapped in for history while Choi two-putted for the triumph.