Melbourne, Australia (SportsNetwork.com) - Lydia Ko fired a final-round, 2- under 71 on Sunday and the world's top player went on to win by two shots at the ISPS Handa Women's Australian Open.

Ko, who became the youngest player ever to reach world No. 1 status at the age of 17 three weeks ago, finished the week at 9-under-par 283. The win is Ko's sixth on the LPGA Tour and her fourth since she turned pro at the start of the 2014 season. She also won twice as an amateur.

"To win on such an amazing course here, it's amazing," said Ko. "I had so much fun when I was playing here in 2012, but to come out on top here and say I beat the golf course is pretty awesome. It's so tough and you can see by the scores that it's hard to make one birdie."

Amy Yang held the outright lead at one point Sunday, but a couple key bogeys down the stretch hurt her. Yang carded a 1-under 72 on the Composite Course at Royal Melbourne Golf Club to finish alone in second at 7-under 285.

Rookie Ariya Jutanugarn, who entered the final round tied for the lead with Ko, shot a 3-over 76 but was still able to finish in sole possession of third place at 4-under 288.

First-round leader Ilhee Lee (71), Jenny Shin (69) and Chella Choi (72) ended tied for fourth at 2-under 290.

The final round was virtually a three-way race to the finish between Ko, Yang and Jutanugarn as the rest of the field sat several shots back throughout the day.

It was an inauspicious for both Ko and Jutanugarn, who were both one shot ahead of Yang heading into the day. Playing in the final pairing, Ko and Jutanugarn tripped to bogeys at the first, dropping them into a three-way tie for the lead with Yang at minus-6.

"I had a shaky start so that kind of got me more nervous," Ko admitted.

Yang then briefly took the outright lead. After making back-to-back pars on one and two, Yang drained her first birdie on three, putting her up one at minus-7.

It was not long-lived, however, as Ko chipped in for eagle on the par-4 third, vaulting her into the lead at 8-under. The eagle was Ko's third of the week.

While Jutanugarn was in the midst of four straight pars from two, Yang tripped to her first bogey on No. 7, giving Ko a 2-shot lead. Jutanugarn then made back-to-back bogeys on six and seven, dropping her four shots off the pace at 4-under.

Then came a 2-shot swing as Ko made her second bogey of the day on eight and Yang poured in a birdie on nine, tying her with Ko for the lead at minus-7.

Following a delay of about an hour due to lightning in the area, Yang's eagle putt on the par-5 10th just lipped out and she settled for birdie, giving her the outright lead.

Both Ko and Jutanugarn went on to birdie 10 as well, pulling Ko even with Yang once again and jumping Jutanugarn up to minus-5, three shots back.

Two holes later, Ko's birdie putt from about 15 feet just made it to the hole and fell to the bottom of the cup, giving her the lead once again. However, that was the last move Ko made on the day as she closed with six straight pars from 13.

Jutanugarn then made a birdie of her own on No. 13 to get within three again, but it was not quite enough as she bogeyed the next two on 14 and 15. She finished with a trio of pars to end five shots back in third.

Yang was still right in it, however. After making three straight pars from 11, Yang made a huge birdie putt on the par-5 14th. Just like that, with four holes remaining, Yang was tied with Ko for the lead once again.

With Ko not making any moves up the leaderboard, Yang began to hurt herself. The 25-year-old missed a short par putt on No. 15 and she made bogey, dropping her out of the lead.

Two holes later, Ko's advantage was cushioned a bit more as Yang missed another par putt and settled for her third bogey of the day.

While Yang made par at the last, Ko coasted to the finish with her six straight pars to earn her sixth career win on tour.

"I think patience is probably the biggest one. You've got to hit good shots, but I think patience was the biggest one that you needed to have," said Ko. "Here there are so many putts that can be so close, but then end up being a couple feet by and you look back and think 'how did I make that bogey?' But it's kind of easy to do. It's hard to make birdies but so easy to make bogeys or worse. I think just patience, that's what I tried to have."

NOTES: Ko finished tied for third at this event last season and ended in sole possession of third in 2013 when she was an amateur ... Ko became the youngest player to win the Australian Open ... Defending champion Karrie Webb (71) finished tied for 16th on her home soil at 1-over 293 ... Only 11 players ended the week under par ... Jutanugarn has now finished tied for second and outright third at her last two events ... With the win, Ko earned $180,000 ... The LPGA Tour heads to Thailand next week for the Honda LPGA Thailand, where Anna Nordqvist earned her third of four career victories with a 2-shot win over Inbee Park last year.