San Diego’s Katherine Hui wins US Open girls’ title as unseeded wildcard

• Hui, 18, tops Valentova 6-4, 6-4 for junior grand slam title
• San Diego native starts first year at Stanford in nine days
• Brazil's Joao Fonseca wins boys' title over Learner Tien

Katherine Hui made it two big victories for American teenagers at the US Open on Saturday, winning the girls' title as an unseeded wildcard in only her second junior grand slam appearance.

Hui, an 18-year-old from San Diego who is entering her freshman year at Stanford, stepped on to Court 12 for her final during 19-year-old Coco Gauff's victory over Aryna Sabalenka for the women's title inside Arthur Ashe Stadium.