NEW YORK (AFP) — Aryna Sabalenka fought back from the brink of defeat to overcome American 17th seed Madison Keys in a third-set tie-break and line up a US Open final against home favorite Coco Gauff.

Keys served for the match in the second set but incoming world No. 1 Sabalenka overhauled the 2017 runner-up to win 0-6, 7-6 (7/1), 7-6 (10/5) to reach her second Grand Slam final.

"She played incredible tennis, it was just another level. Somehow, I don't know how I turned around this match," said Sabalenka, the second seed.

"It really means a lot to be in the final of the US Open for the first time."

Sabalenka rode an emotional rollercoaster, angrily remonstrating with her coaching team at times, before being able to sheepishly laugh off celebrating prematurely in the decisive tie-break.

"I thought that we would play tie-break up to seven," she said.

"I was just all over the place."

The Australian Open champion will bid for her second Grand Slam title on Saturday against the 19-year-old Gauff. The American holds a 3-2 edge but this will be their first meeting at a major.

"She's an unbelievable player," Sabalenka said.

"The crowd will be supporting her a lot. I will do everything I can. I'll be fighting for every point and I will do my best."

Sabalenka handed Keys a break in the first game with a double fault and her troubles were compounded when she again dropped serve after leading 40-0 two games later.

Keys shook off two break chances before a wayward Sabalenka faltered on serve for a third time, allowing her opponent to wrap up the set with ease.

Sabalenka sarcastically raised her arms in celebration as she held to finally get on the board to start the second set.

Keys continued to pump winners with her powerful forehand and broke again for a 2-1 lead, Sabalenka drawing a code violation after smacking a courtside barrier and hurling her racket towards her coach.