China's Zhang Zhizhen and his Czech partner Tomas Machac continue their impressive run as a team by defeating eighth seeds Maximo Gonzalez and Andres Molteni of Argentina 6-3, 7-5 on Tuesday. The Czech-Chinese pair converted three of four break points they earned, en route to an 83-minute third round triumph and will face top seeded pair Marcel Granollers and Horacio Zeballos in the quarterfinals. 

"I want to thank my partner who played very well in the second set because my performance was not that stable. I struggled in my service game and played inconsistently from the baseline. But I adjusted in time and scored some crucial net points to help us win this match," Zhang said.

Zhang and Macha have played two ATP Tour events together. They won an indoor ATP 250 title in February in Marseille, before reaching the semifinals on clay at the Barcelona ATP 500. The duo is now 15-2 for the season and up to 11th in the ATP doubles rankings.