Updated Sep 13, 2015 at 11:29a ET
EVIAN-LES-BAINS, France — Lydia Ko became the youngest major champion in LPGA Tour history at the Evian Championship on Sunday.
The South Korean-born New Zealander closed with an 8-under 63 for a six-stroke victory over Lexi Thompson at the final major of the season.
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.
Ko, who was runner-up in Evian two years ago, enjoyed a remarkable day on the shores of Lake Geneva, staying bogey-free and hitting eight birdies in her final round for the best score of the tournament this year. She finished with a 16-under total of 268.
Mi Hyang Lee, who had an overnight lead of one stroke over Thompson, crumbled under pressure and finished tied for fourth place, nine back. Chinese 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 two 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 but dry 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 2nd then played a three-hole stretch in 3-under. She couldn't stay bogey-free on the front nine, though, missing a putt from close range on the par-3 8th.
Ko enjoyed a clinical start and was one shot behind Thompson at the turn, with three birdies on Nos. 3, 7 and 9.
The Kiwi golfer then hit a wonderful 2nd shot on the par-4 11th that landed on the edge of the green and rolled to within ten feet of the cup, bringing out a big smile on her face and loud cheers and applause from the spectators. Her next shot — a gutsy 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 five feet of the hole. Ko made no mistake with her next putt and moved one shot clear at the top of the leaderboard with six holes left to play. 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.
The pressure of playing for the first time in her career in the final group was too much of a burden for Mi Hyang Lee. She had a big slip-up on the par-4 3rd, where she ended with her first double bogey of the week. After misjudging her second shot into water behind the green, she hit a very good chip to return to the green but the penalty stroke seriously damaged her hopes of clinching a first major. Back-to-back bogeys on the par-3 8th and par-5 9th continued to undo the good work put in during her three previous rounds.
Tied for third place two 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.