Coco Vandeweghe's lost in her last eight match against former winner Maria Sharapova on Tuesday after dumping out sixth seed Lucie Safarova on Monday.
The 23-year-old had never gone past the third round at a Grand Slam before. She's currently ranked 47 in the world.
Speaking ahead of the biggest match of her career, she spoke of the influence of her grandmother while growing up.
She said: "Just being the kind of the presence that she was, she was able to teach me and how to conduct myself.
"Also she made a big deal of me being able to go [to] church and made me do talks in church so I could speak in front of a group of people and be comfortable with that at a young age."
Her passage to the quarter finals will lift her world ranking when the new list is published next week.