Pakistan, Sept. 9 -- Home favourite Coco Gauff and world number two Elena Rybakina sailed into the US Open quarter-finals on Monday, while China's Zheng Qinwen mounted another extraordinary fightback to upset six-times Grand Slam champion Iga Swiatek.

Top seed Alexander Zverev beat Italian Luciano Darderi 6-2 6-2 7-6(3) at Arthur Ashe Stadium, the German surprised to finish before midnight after coming through a couple of five-setters earlier in the tournament.

"I think after 10 hours on court, I just maybe found my rhythm a little bit better, which is helpful because the first two matches were really not great level," Zverev said.

"I think I'm going in the right direction, moving forward in the right direction."

Zverev, who is biddin...