The 19-year-old Pole, ranked world No. 15 by the Women's Tennis Association (WTA), beat No.35 seed Gauff 7:6 (7-3), 6:3 in her second match that day in the Italian capital.
In the morning, she ousted two-time champion Elina Svitolina 6:2, 7:5 in the quarterfinal.
Świątek is now set to battle against World No.9 Karolina Pliskova in the final round on Sunday.
The rising Polish tennis star in February won the Adelaide International tournament in Australia, claiming her second singles title.
Świątek in October won the French Open, claiming her maiden Grand Slam title and becoming the first Pole to lift a Grand Slam singles trophy.
(jh)
Source: PAP