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.

Alexander's latest setback came against the 19-year-old Learnen Tien in the second round in Acapulco. A teenager ousted the Australian Open finalist 6-3, 6-4 in an hour and 28 minutes for his second top-5 victory of the season.

Australian Open finalist Alexander Zverev suffered another setback when he was beaten 6-3, 6-4 by American qualifier Learner Tien in Acapulco. Top seed Zverev lost the last five games from 4-1 up in the second set to crash out in the last 16 match in 1 hour 26 minutes on Wednesday night.

Britain's Cameron Norrie loses in straight sets to American teen Learner Tien in the first round of the Mexican Open.

The up-and-coming Learner Tien defeated World No. 5 Daniil Medvedev at the Australian Open this year and will now be coming up against World No. 2 Alexander Zverev in Acapulco.