Divij Sharan and his Serbian partner Nikola Cacic fought hard before going down in three sets
Bopanna and his Dutch partner Matwe Middelkoop, seeded ninth, were stunned by the unseeded Italian pair of Andrea Vavassori and Lorenzo Sonego
Experienced Indian Rohan Bopanna and his Canadian partner Denis Shapovalo advanced to the second round of the US Open men's doubles event after a straight-set win in New York.
Bopanna and Shapovalov will take on Dutch-Romanian combination of Jeal-Julien Rojer and Horia Tecau in the quarterfinals.
Sania Mirza and Rajeev Ram needed an hour and 27 minutes to defeat the Dutch-Aussie pair of Ellen Perez and Matwe Middelkoop 7-6(4), 6-4.
Mirza, who will retire after the 2022 season, served well in the contest.
Serbia had their backs to the wall when Kazakh veteran Mikhail Kukushkin beat debutant Miomir Kecmanovic in a three-hour epic in the first singles rubber. But Djokovic calmly levelled the tie with a straight-sets defeat of Alexander Bublik before returning to court to team up with Nikola Cacic and beat Kazakh pair Andrey Golubev and Aleksandr Nedovyesov 6-2, 2-6, 6-3.
The winners of the Serbia-Germany tie will join Spain, Russia and Italy in the semi-finals.
World number one Novak Djokovic overpowered Dennis Novak after Dusan Lajovic battled past Gerald Melzer and Serbia went on to a 3-0 win in their opener against Group F hosts Austria in the Davis Cup Finals in Innsbruck on Friday.
Favourites Russia Tennis Federation opened their Davis Cup Finals campaign with a resounding victory over Ecuador, Britain began with a win against France and Italy eased into the quarter-finals with a win over Colombia on Saturday.
Nagal's court coverage and solid defence in long drawn points was the highlight of his win.
Croatia striker Nikola Kalinic believes his country are now one of the favourites at Euro 2016 after beating Spain to win Group D.
Midfielder Andre broke the deadlock for the Euro 2016 finalists in difficult, wet conditions just after the half hour and Nani, celebrating his 29th birthday, scored direct from a free kick in the 89th minute.
Portugal are ready to move up a gear when they face Croatia in their mouth-watering last-16 clash in Lens on Saturday, coach Fernando Santos said.
Substitute Ricardo Quaresma turned in three minutes from the end of extra time as Portugal edged a tense encounter to book a UEFA Euro 2016 quarter-final date with Poland. After 116 minutes in which the teams failed to muster a single shot on target, Ivan Perisic headed against the upright.
Mario Mandzukic and Nikola Kalinic grabbed hat-tricks as Croatia achieved a record win as an independent nation by demolishing San Marino 10-0 in their final Euro 2016 warm-up match in Rijeka.