Alexander Zverev

Third-seeded German Alexander Zverev reached his first ATP semi-final of the season on Thursday, beating Ryan Harrison 6-4, 6-1 to set up a clash with Juan Martin del Potro in Acapulco. World number five Zverev, 20, is the highest-ranked player left in the draw of the hardcourt tournament that saw top seed Rafael Nadal withdraw with nagging hip trouble.