Gauff will play fellow countrywoman Sloane Stephens in a major for the second time in a year.
Paula Badosa was playing in her first career match at the Internazionali BNL d'Italia.
Elsewhere, second seed Simona Halep had reversed a recent loss to Aliaksandra Sasnovich and reached the quarterfinals.
Raducanu struggled under the lights on the stadium court in the Southern California desert on Friday with her accuracy and energy level.