Unforced errors piled as the night wore on and Raducanu never exuded the on-court joy that was a hallmark of her breakthrough despite a supportive crowd.
Gauff, who shot to fame as a 15-year-old when she reached the fourth round at Wimbledon in 2019, urged the 18-year-old Raducanu to take time away from her phone.
The 18-year-old Briton became the first qualifier to win a Grand Slam.
Raducanu, 18, shot to fame this month after she became Britain's first female Grand Slam champion for 44 years.
US Open runner-up Leylah Fernandez jumped 45 spots, climbing from No.73 to No.28.
Raducanu became the first qualifier in the history of the Open Era to win a major title.
The 18-year-old became the first ever qualifier to win a Grand Slam title and the first British woman to hoist a major trophy since Virginia Wade triumphed at Wimbledon in 1977.
Briton Emma Raducanu became the first qualifier to reach the US Open final by beating Greece's Maria Sakkari 6-1, 6-4.
Sakkari leveraged her powerful serve and excellent court coverage to overpower Pliskova and dedicated her win to the people of Greece, who have endured a summer of brutal wildfires.
Emma Raducanu overwhelmed American Shelby Rogers 6-2, 6-1 to reach her first Grand Slam quarterfinal.