The 21-year-old made a stuttering start to the final, with two-time Grand Slam winner Muguruza breaking serve in the third game.

Muguruza continued to force break chances as the Spanish player maintained the momentum from a series of impressive wins at the tournament.

Her momentum briefly stalled when Kenin broke serve, but Muguruza immediately restored her advantage.

She moved a step closer to becoming only the third unseeded player to win the women’s singles title at the Australian Open by serving to take the opening set 6-4.

Kenin continued to grow into the contest and the American was rewarded with a break of serve to take a 3-1 lead in the second set.

She forced the match into a decider by converting another break point chance to win the second 6-2.

Muguruza appeared to have stemmed Kenin’s momentum in the early stages of the decider, but the Spaniard faltered as the tension rose at the Rod Laver Arena.

A double fault on break point proved costly for Muguruza, with Kenin providing a strong service hold to confirm her advantage.

The pressure increased on Muguruza as she served to stay in the match, with a double fault on match point giving Kenin a 4-6, 6-2, 6-2 victory.

Kenin became the youngest Australian Open winner since Russia’s Maria Sharapova won the event in 2008.

“I want to say my dream has officially come true,” Kenin said.

“I cannot describe this feeling, it's so emotional.

“I am so grateful to stand here.

“I would like to thank the crowd, this past two weeks has been the best of my life.”

Defeat prevented Muguruza from securing a third Grand Slam title, following wins at the 2016 French Open and Wimbledon in 2017.

The men’s singles final will take place tomorrow, with Serbia’s Novak Djokovic eyeing his eighth Australia Open crown while Austria’s Dominic Thiem seeks a maiden Grand Slam crown.