Tien defeated Zverev 6-3, 6-4 in an hour and 28 minutes en route to his second top-5 win of the season. Learnen outplayed the third-time Major finalist on serve and return. The young gun dropped serve once and stole 41% of the return points.

Learner Tien, a 19-year-old from California, took down top-seeded Alexander Zverev 6-3, 6-4 on Wednesday to advance to the Acapulco Open quarterfinals.

Zverev, the top seed at the Acapulco Open, went down 6-3 6-4 to the 19-year-old American on Wednesday. Tien, who claimed a big win over Daniil Medvedev en route to reaching the fourth round at the Australian Open in January, came from 1-4 down to win the second set – and the match – by reeling off five straight games.

Zverev is one of several top players in Acapulco who was reportedly affected by stomach issues or food poisoning, with the draw taking a big hit on Wednesday. Casper Ruud and Tomm