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1:02pm (NZ)
"I was able to hit a good shot," she says afterwards. "I didn't know how close it was going to be, but a two-and-ahalf-foot putt to possibly win the event was a pretty good feeling, but nerve-wracking too.
"It's crazy - I was three-over at one stage today, but I just had to focus -you never know what's going to happen - and I was able to put my game together on the back nine."
12:58pm (NZ)
Lee makes the putt - Ko needs this putt to win. She does it!
Brilliant victory for Ko, her third victory on this course.
12:57pm (NZ)
Sorry, Lee missed the bunker, but slides her fringe chip long. That's not a gimme.
12:54pm (NZ)
Holy cow! Ko's second shot dribbles onto the green and passes withi a few inches of the hole - she will have a very makeable eagle putt.
Lee makes yet another bunker, but holed from the last one, so let's just see.
12:48pm (NZ)
They're back to the 18th tee to begin the playoff. Ko hits first - she's down the middle.
Lee hits right, but it straightens to the middle too.
12:38pm (NZ)
Whoa! Ko chips from off the green and misses an eagle by centimetres. Her birdie is enough to force the playoff.
Ko cards a one-under 71 for the day. Meanwhile, Korda pars for a two-over 74, finishing at minus-eight and a share of third.
Ko & Lee -11
Yin, Fen, Hull & Korda -8
Masson, Ashok, Hataoka & A Jutanugarn -7
12:29pm (NZ)
Lee chips to within a couple of metres of the final flag and has a makeable birdie putt for the outright lead - she makes it.
Ko's second shot lands about where Lee was - she now needs up and down to force playoff.
12:26pm (NZ)
Korda bogeys the 17th to drop another shot back, Ko secures her par and Lee leaves her second shot short of the green on the 18th.
12:23pm (NZ)
Korda is out of the bunker, but now has a long putt for par. Ko can retake the outright lead with her birdie putt - but leaves it well right.
12:20pm (NZ)
Ko has a birdie putt on the par-three 17th, but Korda hits into the same bunker that Lee just holed out of.
12:17pm (NZ)
Hull makes birdie on the 18th for a two-under 70 today and minus-eight, tied for fourth.
Only three pairs left on the course now.
Ko & Lee -11
Korda -9
Yin, Feng & Hull -8
Masson, Ashok, Hataoka & A Jutanugarn -7
12:13pm (NZ)
Ko is putting for birdie from the fringe of the 16th green - it's wide left, but makeable for par.
Lee hits into another bunker on the 17th, but holes from the bunker to tie Ko for the lead again.
Korda misses her birdie putt and taps in for par. Ko also makes par.
12:07pm (NZ)
Lee holes her up-and-down putt for par and is still one shot back from Ko.
Ko -11
Lee -10
Korda -9
Yin & Feng -8
Masson, Hataoka, A Jutanugarn & Hull -7
12:02pm (NZ)
Shanshan Feng has carded four-under 68 for minust-eight and a share of fourth for now.
Lee is in another bunker by the 16th green, but chips out safely.
Ko is down the left side of the 16th fairway.
11:57am (NZ)
Korda's eagle putt finishes a couple of feet short, but she has a birdie to move into outright third.
Ko's eagle putt slides by, but her birdie puts her ahead of Lee with three holes to play.
11:53am (NZ)
Lee holes her birdie putt and is now tied with Ko in the lead.
Ko hits within a few metres of the flag and has an eagle putt, but Korda is short of the flag.
11:49am (NZ)
Ko and Korda are safely on the fairway on the 15th.
On the green, Lee has a long eagle putt for the outright lead, but it slides by. She still has five feet for birdie.
11:48am (NZ)
Hataoka has finished with a three-under 69, good for minust seven and currently tied for fifth.
11:44am (NZ)
Ko misses a long birdie putt, but salvages par to retain her lead. Korda misses an easy birdie putt - she has really dropped her bundle, two shots back.
11:37am (NZ)
Ko is safely off the tee on the 14th, but Korda finds the same bunker as Lee, who has dropped a shot.
Ko now leads outright.
Ko -10
Lee -9
Yin & Korda -8
Six players -7
11:34am (NZ)
Korda's birdie putt is left, so no change for her. Lee is out of the bunker, but still has a tricky putt for par.
Yin cards a five-under 67 for the day to finish minus-eighth for the tournament.
11:31am (NZ)
Lee is in a greenside bunker on the 14th hole. Ko chips in from the fairway for a birdie to tie with Lee - that could be a winner!
11:30am (NZ)
Ko's second shot on the 13th lands on the edge of the green and runs back onto the fairway, Korda is within a few metres of the pin with hers.
11:24am (NZ)
Korda and Ko are safely down the 13th fairway with their tee shots, but on the green, Lee holes a birdie putt to take the outright lead from Ko.
11:20am (NZ)
Korda's birdie putt curls left. Ko has a downhill putt, but leaves it left. She makes par, but Korda chokes on hers to drop a shot back.
Hataoka drops a shot at the 16th.
Ko & Lee -9
Korda -8
Masson, Yin & Hataoka -7
Six players -6
11:16am (NZ)
Korda's tee shot finds the green on the par-three 12th - Ko's starts way left, but pitches within a few inches of the hole. She has the shorter birdie putt.
11:14am (NZ)
Ko's par putt slides left, so we have a three-way tie for the lead with Korda and Lee.
Meanwhile, Hataoka has picked up a shot to close within a shot in fourth.
11:11am (NZ)
Nice exit from the bunker from Ko, but she still has a longish putt for par.
Masson has completed her round with 68, sitting tied for fifth on minus seven.
Korda's birdie putt is just right.
11:08am (NZ)
Lee birdies the 11th hole to draw even with Korda in second. Korda finds the centre of the green with her second, but Ko is in a greenside bunker.
Things are getting tight into the back half of the course now.
11:03am (NZ)
Ko slices her tee shot into the trees on the 10th hole, but it bounces out into the rough. She'll have a shot, but Korda is down the middle of the fairway.
Ko -10
Korda -9
Lee -8
Masson, Hataoka & Uribe -7
Yin, Ashok, Hull, M Jutanugarn -6
10:58am (NZ)
Korda's third lands her within a few feet of the flag, but she misses par to fall back a shot. Ko has a chance for a two-hot swing and the lead - she's done it!
10:55am (NZ)
Korda has no shot at the green from where she lies and can only hack it onto the fairway. Ko's second lands within a few feet of the pin, so a great opportunity to snatch a shot back.
10:52am (NZ)
Lee drops a shot on the 10th to fall behind Ko, who is down the middle of the fairway on the same hole. Korda has sliced her tee shot to the right and faces a testing lie for her second.
10:47am (NZ)
Oh no! Ko's birdie putt stops on the lip of the hole. Korda still faces a tricky putt for par, but makes no mistake to maintain her lead.
Korda -10
Ko & Lee -9
Masson, Hataoka, Hull & Uribe -7
Ashok & M Jutanugarn -6
10:43am (NZ)
Ko finds the green and has a longish putt for birdie on the ninth. Korda overshoots the green and finds the fringe, similar to Lee before her.
Speaking of Lee, she's in a greenside bunker with her second shot on the par-four 10th.
10:40am (NZ)
Ko is in good position just short of the green with her second, but Korda has found some rough to the right, with a bunker in play.
Masson picks up another shot and is now tied for fourth at minus-seven.
10:36am (NZ)
Korda and Ko find the middle of the ninth fairway with their tee shots, Lee gets tangled up on the fringe of the ninth green and has a testing putt for her par.
Lee makes her par.
10:30am (NZ)
Korda's birdie putt just slides by, but she saves par. Ko overcooks her putt, but holes her return for par. She's still one back, tied with Lee.
Ashok and Ariya Jutanugarn have dropped shots, Masson has picked one up to move into a tie for seventh with Moriya Jutanugarn.
10:27am (NZ)
Korda finds the middle of the green with her second on the eighth, but Ko is a divet on the fairway - she's also safely on the green with a putt for birdie.
10:25am (NZ)
Lee pars the par-four eighth to remain one back from the lead and tied with Ko for second.
10:21am (NZ)
Korda's tee shot on the eighth runs into the fairway fringe, Ko is down the middle.
10:19am (NZ)
Ko holes her birdie putt to move back into a share of the lead - but Korda also holes to grab it back.
10:15am (NZ)
Korda hits within a few feet of the pin with her second on the par-four seventh and Ko is just a little further astray with hers.
Lee & Korda -9
Ko -8
Hataoka, Hull & Uribe -7
Ashok, A Jutanugarn & M Jutanugarn -6
10:13am (NZ)
Lee moves into a share of the lead with a birdie on the seventh, Hataoka and Hull have birdies to draw with one of Ko and two of the lead.
10:11am (NZ)
Ko drops that shot and falls behind Korda, now tied with Lee in a tie for second. Ko is now three-over for the day.
10:05am (NZ)
Ashok has jumped into a five-way tie for fifth spot with a birdie on the eighth - they're three shots back.
Ko is out of the bunker, but has a long putt for her par on the sixth.
10:01am (NZ)
Regulation pars for Ko and Korda on par-five fifth. Korda is on the green with her tee shot at the sixth, but Ko finds a bunker.
9:52am (NZ)
Minjee Lee picks up a shot at the par-five fifth to close within a shot of the lead.
9:45am (NZ)
Ko drops a shot at the par-four fourth and is now tied with Korda in the lead.
9:42am (NZ)
Feng drops a shot at the par-five fifth to slide into a seven-way tie for eighth with Altomare, Masson, American Angel Yin, Indian Aditi Ashok, American Ryann O'Toole and Thai Moriya Jutanugarn.
9:33am (NZ)
Ko and Korda score pars at the par-three third to maintain their standings.
The wolves are gathering a little further down the table - Chinese Shanshan Feng is two-under for the day, Thai Ariya Jutanugarn has picked up a shot and Englishwoman Charley Hull is all square - they're tired for sixth at minus-six.
Altomare is now six-under for the day, a shot back in ninth.
Ko -10
Korda -9
Hataoka, Uribe & Lee -7
Feng, A Jutanugarn & Hull -6
Altomare -5
9:28am (NZ)
Minjee Lee drops a shot on the par-three third and Hataoka picks up another at the par-four eighth - they're in a threeway tie for third with Uribe, three shots back from Ko.
9:20am (NZ)
Pars for Ko and Korda on the par-four second hole, still Ko by one.
There's a bit of banter about Korda's dress code...
9:17am (NZ)
Amiercan Brittany Altomare is also moving through the field - she began the day tied for 38th, but is now in 12th, picking up five shots through 17 holes.
German Caroline Masson is two-under for the day and minus-five overall, tied in seventh.
9:13am (NZ)
Back in fourth, Colombian Mariajo Uribe has picked up a shot - a birdie on the second - and is now just three shots behind Ko.
9:07am (NZ)
Bad news - Ko's round has begun and she dropped a shot on the opening hole. Luckily, playing partner and closest rival Jessica Korda also dropped shot, so Ko still has that one-shot advantage.
Their bad luck does bring Australian Minjee Lee into play - she now lurks just one shot behind Korda on eight under.
8:52am (NZ)
Another big mover has been American Jaye Marie Green, who is four under through 10 holes today and minus-five for the tournament. She started today's round with four pars, but got rolling with an eagle on the par-five fifth, and then a birdies on the sixth and ninth.
8:36am (NZ)
Let's quickly catch up on who's making the moves from the early tee times at Lake Merced.
Biggest mover so far has been American Lizette Salas, who is already in the clubhouse with a three-under 69, promoting her 20 spots to a tie for 32nd.
Higher up the leaderboard, Japanese Nasa Hataoka is two under through three holes and is now tied for fourth at minus-six for the tournament, still five shots behind Ko.
Remember, Hataoka was tied with Ko briefly yesterday, but they went in opposite directions as the day progressed.
**********
Good morning and welcome to Lake Merced Golf Club in San Francisco for live updates of Lydia Ko's final round at the Mediheal Championship.
The 21-year-old as a one-shot lead at 11-under and hasn’t won on the LPGA circuit since July 2016. Ko tees off at 8:50 am (NZ time).
Ko has two previous victories at Lake Merced, in 2014 and 2015, among her 14 LPGA Tour wins.
The Kiwi will be partnered with American Jessica Korda - who tees off at the same time.
Pre-round banter: Leading Lydia Ko keeping calm ahead of final round
Kiwi Lydia Ko is trying to keep her emotions in check as she is within touching distance of winning her first LPGA title since July 2016.
The 21-year-old as a one-shot lead at 11-under after an impressive five-under round of 67 during the third round on Sunday at the Lake Merced Golf Club in California.
Ko has two previous victories at Lake Merced, in 2014 and 2015, among her 14 LPGA Tour wins.
She is trying to keep calm as she eyes her first title in nearly two years.
"I guess if it happens, I'm sure I'll be super excited. Who knows? It might be tomorrow, it might be the next week, might be in the year, who knows?
"I know that no matter what number win it is, it's always exciting to be the one holding the trophy.
"I think it would be emotional and exciting for not only me, but for my whole family."
Ko said she feels comfortable playing at one of her favourite courses.
"I love San Francisco, and I'm a member here, so sometimes I get some friendly member bounces. But it brings back a lot of good memories for me.
"Coming into the week, I knew that no matter how I was going to play, I knew I was going to have a great time. The members here and all the fans have been super supportive."
Ko will begin her final round at 8:50 am (NZ time).
Newshub.
