EVIAN-LES-BAINS, France -- With two holes left to play in her bid to become the youngest LPGA major winner, Lydia Ko stayed as relaxed and composed as a seasoned veteran at the Evian Championship. The South Korean-born New Zealander birdied both on the shores of Lake Geneva to reach a new landmark in her short but already storied career.
With a flawless final-round display that featured spectacular approaches and clinical putts among her eight birdies, Ko became the youngest major champion in LPGA Tour history Sunday. She closed with an 8-under 63 for a 6-stroke victory over Lexi Thompson at the final major of the season.
It was the best round of this year's tournament, a score that helped her to a ninth career victory with a 16-under total of 268.
"It's probably the best round ever," Ko said. "To finish with two birdies, finish on the last 72nd hole, with a birdie, it doesn't happen often, so it's definitely one of the top rounds of my whole entire life, and I'm sure it will be in my career."
Ko is 18 years, 4 months and 20 days old. She eclipsed the previous record set by American Morgan Pressel, who was 18 years, 10 months and nine days old when she won the 2007 Kraft Nabisco Championship.
While Ko thrived under pressure, Mi Hyang Lee crumbled. The South Korean had an overnight lead of 1 stroke over Thompson but finished tied for fourth place, 9 back. China's Shanshan Feng was third with an 8-under total of 276.
"Everyone won't be asking me when I'll win my first major because it's done," said Ko, who was 2 shots off the pace heading into the final round.
Ko has been breaking records even before she turned professional two years ago.
Tipped as a future great of the game, she was already the youngest winner on the Tour after her win at the Canadian Women's Open in 2012, and the youngest player of either gender to reach the No. 1 spot when she did it earlier this year.
On a damp morning, she kept her cool when Thompson got off to a flying start.
Ko, Thompson and Lee were grouped together after organizers decided players would tee off on the first and 10th tees in threesomes fearing expected bad weather would play havoc with the schedule. The elite trio started with a par on the first hole before Thompson set a tremendous early pace with four birdies in her first seven holes. The American converted a long putt for birdie on the par-3 second then played a three-hole stretch in 3 under from Nos. 5-7. She couldn't stay bogey-free on the front nine, though, missing a putt from close range on the par-3 eighth.
"It's definitely one of the top rounds of my whole entire life, and I'm sure it will be in my career. ... Everyone won't be asking me when I'll win my first major because it's done." Lydia Ko, 18, after winning the Evian Championship on Sunday
"It's kind of hard to beat somebody that shoots 63," said Thompson. "She played amazing. She deserves it. She ball-struck the heck out of this golf course and putted it really well. You can't get much better than that."
Ko was 1 shot behind Thompson at the turn, with birdies on Nos. 3, 7 and 9.
The Kiwi golfer hit a wonderful second shot on the par-4 11th that landed on the edge of the green and rolled to within 10 feet of the cup, bringing out a big smile on her face. Her next shot -- a downhill birdie putt -- found the hole to draw level with Thompson at 12 under.
That shot signaled a swing in the momentum.
Ko came close to an eagle on No. 12 but her ball hit the flagpost and bounced, stopping within 5 feet of the hole. Ko made no mistake with her next putt and moved 1 shot clear at the top. She capped her day in style with consecutive birdies on Nos. 17 and 18.
For Thompson, things took a turn for the worse on the par-3 14th. She landed her drive on a rough patch behind the green and a poor recovery shot left her fuming as she hit the grass twice with her club and settled for a double-bogey that sealed her fate.
Lee had a big slip-up on the par-4 third, where she ended with her first double-bogey of the week after misjudging her second shot into water behind the green. Back-to-back bogeys on the par-3 eighth and par-5 ninth continued to undo the good work put in during her three previous rounds.
Tied for third place 2 shots off the pace after the third round, Morgan Pressel had two birdies and six bogeys for a 4-under total of 280 that saw her drop to a tie for 11th place.
Ko had a chance to reclaim the top spot in the Rolex Rankings, but top-ranked Inbee Park stayed out front after finishing tied for eighth.