Japan's Naomi Osaka has become the new women's world number one after winning the Australian Open final against Petra Kvitova in three gripping sets at Melbourne Park.

Key points: 21-year-old Japanese star Naomi Osaka has won the Australian Open women's singles title, beating Czech player Petra Kvitova 7-6 (7/2), 5-7, 6-4 in the final

21-year-old Japanese star Naomi Osaka has won the Australian Open women's singles title, beating Czech player Petra Kvitova 7-6 (7/2), 5-7, 6-4 in the final Osaka — who won last year's US Open title — now takes over as the world number one from Romania's Simona Halep

Osaka — who won last year's US Open title — now takes over as the world number one from Romania's Simona Halep Kvitova was playing her first Grand Slam final since recovering from a serious hand injury sustained in a knife attack at her home in 2016

Osaka backed up her victory in last year's controversial US Open final against Serena Williams to claim her second major title, beating Kvitova 7-6 (7-2), 5-7, 6-4 in two hours and 27 minutes at Rod Laver Arena.

She becomes the first Japanese player to hold the number one ranking, moving up to the top spot from number four.

It had appeared Osaka was headed for a straight-sets win when she held three championship points at 5-3 in the second on the Kvitova serve.

But the Czech eighth seed showed nerves of steel to save all three and hold serve, much to the frustration of her 21-year-old opponent.

Even at that point, given the strength of the Osaka serve, it seemed the fourth seed would be able to safely serve out the set.

Kvitova, however, broke Osaka and secured a second break in a four-game winning streak to clinch the set and force a third and deciding set.

Naomi Osaka went through a range of emotions in the second set. ( AP: Aaron Favila )

Osaka seemed rocked by wasting her chances and she briefly left the court crying between the second and third sets.

But she found her composure early in the third to break Kvitova's serve and it was an advantage she was able to maintain to close out her win.

She then showed her class when she preferred to praise Kvitova rather than bask in the glow of her win.

"I always wanted to play you and you have been through so much," Osaka said at the presentation ceremony.

"Honestly I wouldn't have wanted this to be our first match.

"Huge congrats to you and your team and you are really amazing and I am really honoured to have played you in the final of a Grand Slam."

It would be a most satisfying victory for Osaka, given her win in the US Open final was overshadowed by the drama surrounding Williams.

The presentation ceremony in New York had been marred by booing, which seemed aimed at chair umpire Carlos Ramos, and a tearful Osaka had to be comforted by Williams, who had been handed a game penalty among three violations during the final.

She also had to deal with significant media attention in Melbourne this week, after one of her sponsors was forced to apologise for "whitewashing" her in a cartoon advertisement.

Petra Kvitova makes a forehand return to Naomi Osaka. ( AP: Aaron Favila )

It was also a performance from which two-time Wimbledon champion Kvitova can draw enormous pride, considering her career almost ended when she was the victim of a vicious home invasion in late 2016.

She was held at knifepoint and was stabbed in her left hand, sustaining severe injuries which doctors thought would mean she would never play tennis again.

Kvitova returned to the WTA tour the following year and Saturday night's final was her first appearance in a major tournament decider since the attack.

"It's crazy," an emotional Kvitova said.

"I can hardly believe that I just played in a Grand Slam [final] again."

Check out how Osaka's win unfolded in our blog below.