Juan Martin del Potro tops Alexander Zverev to reach Shanghai quarterfinal

SHANGHAI (AP) — Juan Martin del Potro advanced to the Shanghai Masters quarterfinals by overcoming third-seeded Alexander Zverev 3-6, 7-6 (5), 6-4 on Thursday.

Del Potro required four match points - two on Zverev's serve in the ninth game, two on his own serve in the 10th - to win this first encounter career against the German.

Del Potro, who lost his serve for the only time in the match in the second game, won nine of his 15 service games at love.

"I'm happy with my success as I played one of the good guys on tour, he's been playing so good this season," del Potro said. "This was a positive for me looking to the future."

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Zverev, who was in the hunt for a sixth ATP title of the season, lost his composure after netting a backhand to surrender his serve in the fifth game of the third set to the Argentine.

Zverev whacked his racket on the court. That didn't satisfy his anger so he kept smashing the racket courtside until it was a mangled mess.

"For me, it's impossible to lose a match when I've only been broken one time," Zverev said. "The game where he broke me I was up 40-15 and I was just unfocused there."

Del Potro, a 2013 Shanghai finalist, was aware he made a likely permanent impact by breaking Zverev's serve.

"I saw his frustration, for sure," he said. "He's still very young and has to keep learning. He has everything to be in the top of the game."

Earlier, sixth-seeded Grigor Dimitrov of Bulgaria got past Sam Querrey of the U.S. 6-3, 7-6 (3) in the round of 16. Fourth-seeded Marin Cilic defeated another American, Steve Johnson, 7-6 (1), 6-4.