Lee, the 21-year-old Australian who won the 2012 U.S. Girls' Junior at Lake Merced, hit her second shot into the rough near the right greenside bunker and made a 10-foot birdie putt.
The former world No.1 went head-to-head with Australia's Minjee Lee through the final few holes of the Mediheal Championship, ultimately winning a sudden-death playoff hole to secure her first tour triumph since July 2016.
"Yeah I hit some really good three woods today and I said 'hey you got to maybe try copy the one on the other par five.' I was able to hit a good shot again and I didn't really know how close it was going to be", Ko told Golf Channel's commentator Jerry Foltz.
In 2016, while at No. 1 in the Rolex Rankings, Ko overhauled all aspects of her game.
If Ko was nervous about winning for the first time in almost two years she certainly wasn't showing it.
She broke down in tears as the reality sank in.
"It's insane because I was 3 over for the day at one stage and I said, 'Hey, you've just got to focus and you never know what's going to happen, '" Ko said.
"I actually thought my putt might go in the first time I played the 18th hole. But just to have a two and a half footer to possibly win the event is a pretty good feelingbut nerve-racking too.a lot of emotions". "I think it was more frustration against myself from myself".
"Sometimes self pressure is the biggest thing". I put a lot on my shoulders and I've been trying to release it.
"I used to be a player, you know".
Sunday, that never-quit attitude earned her a 15 career win on the LPGA Tour.
A leaner Ko has faced continuous scrutiny over changes of coaches and caddies as she plummeted from being the world number one to 18th.
Her victory came at one of her favourite courses, where she is a member.
But Ko had even better history there, having won the LPGA Swinging Skirts tournament at the tree-lined layout in 2014 and 2015. "This is such a special place for me", she said.
There had been huge excitement over the closing stages of the regulation round.
Ko matched the low round of the third day with a 67 to lead by two at 11-under par, one ahead of Jessica Korda.
Thailand´s Moriya Jutanugarn, who claimed her first LPGA title last week in Los Angeles, signed for a 71 and headed a group sharing fourth on 210 that also included Colombia's Mariajo Uribe (68), American Ryann O´Toole (69) and England´s Charley Hull (73).
That left Ko needing an eagle on the 18th for outright victory. She nearly did that, chipping to within centimetres of the hole on the par five but she had to settle for birdie and a playoff.
- 21st Century Fox (FOXA) Short Interest Update
- Allegri Credits Juve Win To San Siro Wonderful Atmosphere
- Brokerages Expect Baxter International (BAX) to Announce $0.62 Earnings Per Share
- ValuEngine Lowers H&E Equipment Services (HEES) to Hold
- Fortinet Inc (NASDAQ:FTNT) Sellers Covered 10.08% of Their Shorts
- China Open: Alexander Bjork secures first European Tour title
- Pyongyang offers to close n-test site next month, says Seoul
- Gonzales, bats help Mariners beat Cleveland
- Qep Resources Target of Unusually Large Options Trading (QEP)
- Rafael Benitez: 'Newcastle United players must think about the future'