A three-wood from over 230 yards on a cool breezy North Californian day at the first playoff hole set up an eagle and Ko's 15th victory on the LPGA Tour against Lee who has long been a contemporary of Ko's through amateur and professional golf.
Ko’s win, her first in nearly two years on the LPGA Tour, was made even sweeter as it came during a week in which she celebrated her 21st birthday.
"I hit some really good three woods today but I said hey you have to try and copy that one on the other par five," Ko told Golf Channel soon after her win.
"I didn't know how close it was going to be but just to have the 2½ footer to win the event is a pretty good feeling but also nerve-racking too."
For Ko the victory is her third over the Lake Merced Golf Club layout and will perhaps help quell a lot of scrutiny over the many changes she has made and the speculation as to whether they have been good for her game or otherwise.
The emotion she displayed after holing the putt to win must in some way be attributed to her decisions and those of her support group being vindicated by what was a tough hard fought win on a quality golf course.
Unforgettable final round by Lydia KoApril 30, 2018
Ko began the day with a one-shot lead over Jessica Korda but when she bogeyed three of her first six holes she was behind both Korda and Lee with Korda actually taking the lead outright at the 7th when she birdied to move one ahead of Lee.
Korda though would stumble early in her back nine and it would be left to a nip and tuck battle between Ko and Lee over the closing eight holes to determine the winner.
Ko chipped in for a birdie at the 13th to join Lee in the lead and when Lee bogeyed the 14th she fell one back.
Lee would birdie the 15th but so too would Ko although Lee would also hole from off the green at the 17th when a bunker shot found the cup and the pair was tied.
Ko almost stole the title at the 72nd hole when she came so close to holing her eagle pitch from just short of the green but with Lee having birdied that same hole 10 minutes earlier it was back to the 18th tee to determine the winner.
Both players found the fairway but Ko was over 20 yards shorter than Lee. She would, though, hit one of the most exquisite fairway wood shots, especially given the pressure she was under to do so.
The shot was always on line and ran past the edge of the cup to just over two feet.
Lee birdied after missing the green with her approach before Ko took her first title since the 2016 Marathon Classic in Ohio.
Korda would eventually fall back into a share of third after a tough day on the greens, a position she shared with Angel Yin, Shanshan Feng and Charley Hull.
The other Australians to make the cut were Su Oh who tied for 18th after an encouraging and improved week and Hannah Green who was well back in 58th place.
SIGNATURE HOLES: 14TH AT CRONULLA (NSW)
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