Sabalenka may be second in the rankings to Iga Swiatek, but she is arguably the best Grand Slam player in the women's game.

She has reached the final of the past four hard-court majors, winning two Australian Open titles, and has made the semi-finals stage or better at seven of her past eight Slams.

Pegula has also broken new ground, having previously lost all six of her Slam quarter-finals, before toppling Swiatek on Wednesday.

The daughter of Buffalo Bills' owner Terry, Pegula has poked fun at misconceptions about her lifestyle, saying people expect her to have a butler because of her family's wealth.

She has taken the subway to Flushing Meadows most days, documenting it on Instagram, and has spoken of the support she received from her parents.

Pegula struggled with injuries in her early days before making a steady rise up the world rankings, but a Slam title has remained elusive.

"It's amazing. It's a childhood dream. It's what I wanted when I was a kid," the 30-year-old said.

"It would mean the world to me to win. If you would have told me at the beginning of the year I'd be in the finals of the US Open, I would have laughed so hard."