Underdog Madison Keys upset Aryna Sabalenka 6-3, 2-6, 7-5 in the Australian Open final on Saturday to win her first Grand Slam crown at the age of 29.

The American ended world number one Sabalenka's dream of becoming the first woman for 26 years to win a third successive Melbourne Park singles title.

Keys yelled in delight and wiped away tears on securing the title after withstanding a fierce fightback from the Belarusian two-time defending champion.

Sabalenka, the 2023 and 2024 champion, buried her head in a towel after her 20-match win streak at Melbourne Park was ended.

For 19th-seeded Keys it was the culmination of a 15-year journey from teenage prodigy to major winner.

"I have wanted this for so long and I have been in one other Grand Slam final and it did not go my way," said an emotional Keys, whose coach Bjorn Fratangelo is also her husband.

"I didn't know if I was ever going to get back to this position to try to win a trophy again.

"I'm mostly just really proud of myself to get back to this position, to be able to play the way that I played and finish on such a strong note."

The American had been tipped as a future world number one after winning her maiden WTA Tour match at the age of 14.

She made her first major semi-final at Melbourne Park 10 years ago as a 19-year-old, but a decade on she can finally call herself a Grand Slam champion.

"I made my very first Grand Slam semi-final here in Melbourne," said Keys, the runner-up at the US Open in 2017.

"So to now have won my first Grand Slam in the same place means the absolute world to me.

"My team believed in me every step of the way. So thank you so much," added Keys, who will now equal her career-high seventh in the world ranking she attained nine years ago.

"They believed in me when I didn't believe in myself and helped me every step of the way. Last year was so tough, with some really bad injuries, I didn't know if I was gonna be able to do it again." (AFP)