‪Say hello to the #DBOpen semi-finals, @mackiemacster! 👋 The 23-year-old 🇺🇸 scores the biggest win of his career after defeating del Potro 6-4, 3-6, 7-6(5). Next up: Radu Albot... 📸: Andrew Patron/@delraybeachopen _ #USTennis #MackenzieMcDonald #Tennis