It is doubtful New Zealand sport has ever had such a prodigious talent to match Lydia Ko at such a tender age.
Sport is loaded with gifted performers yet to blow out 21 candles, but who fail to press on and match the deeds of their teens, so there are dangers of getting ahead of oneself.
Ko has all that ahead of her. She will have dog days along with, hopefully, many memorable ones. The sports performer who has enjoyed untrammelled success throughout his or her career hasn't been born yet.
But 15? Come on.
The youngest winner on the LPGA Tour, US amateur champion, youngest winner of a professional tournament (the New South Wales Open, at 14, last year). The first New Zealander to win the country's women's Open this year, and a course-record 10-under on the opening day of the Australian Open in Royal Canberra on Thursday.
With whom can Ko be compared? Just think golf a moment.
Remember when Michelle Wie was going to blaze a trail through the women's game a few years ago. She's worth a bundle but at an ancient 23 how many PGA titles has she won? Two.
Indeed, she was one of Ko's playing partners as the bespectacled New Zealander sliced the Royal Canberra course apart.
"She's a phenomenal player," Wie said. "She just seems like a kid, so I hope she stays that way and just enjoys it." There's a good reason for that.
Cast your mind about for other New Zealand sports men and women who might, just, compare.
Danyon Loader was an Olympic Games silver medallist at Barcelona 21 years ago, aged 17. He went on to double gold in Atlanta in 1996, aged 21. Phenomenally good by the most exacting global standards, at a young age? Absolutely. Then he was gone. That's swimming for you.
The gifted Bernice Mene was at high school when called into the Silver Ferns; Jeff Wilson was 19 when he first played for New Zealand at cricket; 20 when, later the same year he pulled on the All Blacks jersey.
Martin Crowe was 12th man for Auckland aged 15.
His test career began against an unforgiving Australian attack in 1982, at 19.
In time, that rough introduction long gone, if not forgotten, Crowe went on to become one of New Zealand's finest batsmen.
Dan Vettori, chosen for his test debut at 18 years 10 days, against England in 1997, is New Zealand's youngest international and has gone on to a career of high accomplishment, which is still running, albeit derailed by injury of late.
Wynton Rufer's goals helped New Zealand qualify for the 1982 World Cup. He was 19 and a stellar career at German Bundesliga club Werder Bremen ensued.
Rufer's misfortune, if it can be so called, is that his most notable achievements were overseas, and therefore out of sight to the New Zealand sports public.
We still recall how Anna Kournikova was going to take the tennis world by storm. She did, but not for her results. Barely remembered now, she failed to win a single WTA title.
Fellow racket wielder Michael Chang won the French Open title at 17 in 1989, but that was to be his grand slam lot.
Nadia Comaneci was scoring perfect 10s in the gymnastics arena at 14 in the 1976 Olympics.
Mushtaq Mohammad, one of the celebrated Pakistani cricket clan, made his test debut in 1959, aged 15. He was an outstanding player over a 20-year career.
His countryman Hasan Raza ridiculously started a year younger in 1996. He is now 30 and hasn't played a test for eight years.
Weird are the ways of Pakistani cricket.
Tiger Woods didn't win the first of his 75 PGA Tour titles until he was 20.
So no, Ko is not quite at the top of the mountain in terms of achievements in one so young. But just think, in five years' time she still won't be 21.