Nerveless Lydia Ko closed with a dramatic final hole birdie to claim her second major today at the ANA Inspiration in California.
Ko laid up on the par five 18th then speared a wedge inside three feet and holed the putt while her closest rival Ariya Jutanugarn hooked her tee shot into the water guarding the left side of the fairway.
It compounded a series of errors Juatanugarn made in the final three holes while Ko kept her round intact with some superb recovery wedges and steely putting as Jutanugarn bogeyed under the rising pressure.
Ko maintained the heat up the last while Jutanugarn folded as she did three years ago in the Thailand Open when she was searching for her maiden victory but tripled the last par five hole and lost by a shot to Inbee Park.
It's been a remarkable year for world No 1 Ko who won in Carlsbad last week as an entrée to the opening major.
"You know there were some putts where I said hey if you hole this you still have a chance but I did not get to see the leaderboard on what the girls were doing behind until 17," she said.
"I'm proud I was able to make those clutch putts especially on the back nine."
Coach David Leadbetter claimed she was in the best ball-striking shape of her career and was ready to make amends for previous problems at the ANA where her best finish was tied for 25th.
Listen: Lydia Ko on winning her second LPGA major
Ko became the youngest major winner last year at the Evian Championship and is now the youngest winner of successive majors before she turns 19 later this month.
Ko shot 70, 68, 69, 69 around the Rancho Mirage course before in the winner's tradition, she made the leap into Poppie's Pond which guards the final hole. The Kiwi won by a shot from Charley Hull and playing partner In Gee Chun and takes her tally to 12 LPGA victories.
Tenacity and technique were Ko's allies as she did not make a bogey in her last 41 holes.
Her driving and iron play was not at its sharpest in her final round when she missed three fairways and six greens.
However she got up and down from her solitary bunker and had just 27 putts as she refused to concede any ground to par on the difficult Rancho Mirage course.
Jutanugarn charged through the middle of her round with four birdies in five holes to open up a handy lead however she fell to the combined pressure of the moment and Ko's intense finish.
Ko celebrated her ANA Inspiration tournament win by doing the traditional leap into Poppies' Pond.