Djokovic's exit means there will be a first-time Grand Slam champion in the men's draw, with Zverev among the contenders at Flushing Meadows.
In the women's singles, fourth seed Naomi Osaka of Japan finished a routine job as she eased past Anett Kontaveit from Estonia 6-3, 6-4 to reach the quarterfinals.
"We all trained very hard, and I want to thank all the players,"
R&F broke the deadlock while Saba forced Jianye defender Chen Hao into an own goal in the 12th minute.
The women's one-hour race saw a close battle between Hassan and Kenya's world marathon record-holder Brigid Kosgei. The duo stayed well ahead of the world record pace as they exchanged the lead several times but neither managed to break clear.
"He's one of the big champions of the last decade, one of the very few active players, who won a Grand Slam tournament here in New York," Thiem said of Cilic. "Even though he's not on the top of his game, he's always dangerous for a deep run in these big tournaments. He's not a guy I want to face in the third round as he's a former champion. On a good day, he can beat anybody."
Hunan Hualai ranks third after sweeping Jiangsu Weikeduo 5-0 on Tuesday, with their opponents remaining at the bottom with no wins.
Last season saw goalkeeper Thibaut Courtois show why Madrid signed him from Chelsea, while the defense of Sergio Ramos, Raphael Varane, Dani Carvajal and Ferland Mendy was the tightest in the league.
In the other Group B game here on Sunday, Alan Kardec and Adrian Mierzejewski brought Chongqing Dangdai Lifan a 2-0 lead in the first half. After Hui Jiakang narrowed the gap to one in the 62nd minute for Teda, Felix Bastian's penalty was denied by Chongqing goalkeeper Deng Xiaofei in the 85th minute.
The Bayern defender refers to the fact that most of Germany's new faces have known each other for many years, having played in the same club or Germany's youth teams.
Rodriguinho had given Bahia the lead at Internacional's Beira-Rio stadium when he cut onto his left foot and slotted a low shot into the bottom left corner.