Despite oppressive temperatures that hovered in the 90s in New York on Tuesday, Coco Gauff barely had to break a sweat to reach her first U.S. Open semifinal.

The 19-year-old American No. 6 seed destroyed No. 20 Jelena Ostapenko, 6-0, 6-2, in 68 minutes in the quarterfinals in Arthur Ashe Stadium. Gauff is now 16-1 since losing in the first round of Wimbledon and adding Brad Gilbert to her coaching team.

In Thursday’s semifinals, Gauff, one of five American men and women in the quarterfinals, will meet the winner of Tuesday’s night match between No. 10 Karolina Muchova and No. 30 Sorana Cirstea. The women’s final is Saturday afternoon.