In ending the title dreams of great home hope and world No.1 Ashleigh Barty with an unexpected 7-6 (8-6) 7-5 triumph, Kenin moved within one win of becoming the first American man or woman to win a major title since Sloane Stephens at the 2017 US Open.

"I always believed I can (do this)," said the 21-year-old Kenin, who at the age of seven famously described how she would go about returning the great Andy Roddick's serve in a video which has recently gone viral on Twitter.

"Of course I didn't have a book.

"I didn't know exactly when.

"I feel like at this young age, I think it's incredible.

"Not everyone gets to live this moment, live this dream. I'm just really grateful for it.

"I've worked so hard. I've put all the efforts into my practices, into my fitness.

"All the efforts I've been doing, it's got me here.

"It's just paying off and it's like a dream come true for me."

Retired former men's world No.1 Roddick was among the first people to congratulate Kenin on her victory.

"This girl has become the goods! Kick ass and bring home the title @SofiaKenin. So cool," he tweeted.

The 14th-seeded Kenin will play Spaniard Garbine Muguruza in Saturday night's final after the two-time major winner ousted Romanian Simona Halep 7-6 (10-8) 7-5.

Barty was gracious enough to acknowledge that the American played the big points better on Thursday in a semi-final played in sweltering heat before a parochial crowd on Rod Laver Arena.

The Moscow-born Kenin saved two set points in each set before securing a victory which ensured she would break into the world top 10 for the first time.

"I was telling myself, I believe in myself," she said.

"If I lose the set, I'm still going to come out and believe.

"I really did a great job with it and I didn't give up.

"I knew it was a tough match.

"Of course, some things didn't go my way with the challenges and some great shots she came up with, but I didn't let that stop me.

"I left everything out all on the court, so it paid off."

Kenin had a breakthrough victory against her idol Serena Williams in the third round of last year's French Open before losing in the next round to eventual champion Barty.

Australian Associated Press