Teenage world No.1 Lydia Ko can now add Australian Open champion to her lengthy list of achievements with a two-stroke win at Royal Melbourne on Sunday.

The 17-year-old New Zealander became the youngest-ever world No.1 earlier this month and is now the youngest player to win the Australian Open crown.

It was her first tournament victory since moving atop the world rankings.

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Despite the hot and steamy conditions on Melbourne’s sand-belt, a cool and calm Ko finished at nine under overall to claim the tournament from Gold Coast-raised South Korean Amy Yang.

The pair duelled for the lead through the final round, with Yang carding a one-under 72 to finish at seven under.

Thailand’s Ariya Jutanugarn was third at four under after a final round 76.

The best Australian finisher was another teenager, Minjee Lee, who was in a tie for seventh at one under for the tournament after closing with a 72.

Ko and Yang duelled throughout the final round, with an 90 minute suspension of play for lightning helping Ko’s cause.

While Ko had just dropped a shot on the eighth, Yang, had birdied nine and was ready to putt for an eagle on 10 when the siren sounded.

Yang settled for a birdie after her ball circled the hole but failed to drop.

It gave her the lead but it didn’t last long with Ko adding two birdies on the back nine.

Yang also had two birdies but bogeys on 15 and 17 snuffed out her challenge.

“I think that break was really good for me,” Ko said.

“I had some lunch and got my stuff together there and I played much better after that.”

Ko’s record also includes being the youngest golfer to win a professional event, taking out the women’s NSW Open when she was 14.

She said she loved playing in Australia and approached each tournament here with the mind-set she could win.

“I’ve always played well in Australia, so it’s always cool coming back here,” she said.

-AAP