Diego Schwartzman has pulled out a major upset at the US Open…

The 27-year-old Argentine professional tennis player defeated No. 6 seed Alexander Zverev at Flushing Meadows 3-6, 6-2, 6-4, 6-3 to advance to the quarterfinals at the Grand Slam event for the second time.

Zverev doubled-faulted 17 times in the losing effort, and he ended up losing his serve eight times, won just 32% of second-serve points and amassed 65 unforced errors. He also was hit with a point penalty for swearing in the final set to put Schwartzman up 5-2.

“My first serve is still fine. My second serve needs to be worked on,” Zverev said. “But I’ll deal with it.”

The 20th-seeded Schwartzman, meanwhile, went about his steady baseline and retrieving game, taking the majority of long rallies in a match when some points went on for as many as 35 strokes.

Schwartzman, who reached the quarterfinals at the French Openlast year and at Flushing Meadows in 2017, next takes Rafael Nadal.