Holders Serbia completed a 4-1 Davis Cup victory over India on Sunday with Germany joining them in the quarter-finals after Philipp Petzschner clinched victory in a thriller in Croatia.
World Group debutants Kazakhstan provided the biggest shock of the first round, winning both of Sunday’s reverse singles to beat the Czech Republic 3-2 in Ostrava.
Last year’s runners-up France also squeezed through despite a valiant Austrian fightback in Vienna.
Andy Roddick smoothed the United States’ path to a quarter-final match at home to Spain, beating Chile’s Paul Capdeville to give his side a 3-1 lead in Santiago.
Spain, Argentina and Sweden had all wrapped up their World Group first round ties by taking unassailable leads over Belgium, Romania and Russia respectively on Saturday.
World number one Rafael Nadal used Sunday’s dead rubber as some useful practice, beating Belgium’s Olivier Rochus 6-4 6-2.
Unfancied India had fought toe-to-toe with Serbia in Novi Sad during Friday and Saturday to trail 2-1. Serbia’s Viktor Troicki, playing as his country’s top player in the absence of world number three Novak Djokovic, finished the job.
Troicki, who won the decisive fifth rubber when Serbia beat France in last year’s final in Belgrade, was too strong for Somdev Devvarman, winning 6-4 6-2 7-5 in the first reverse singles to set up a July quarter-final in Sweden.
“It is a great feeling to be in the last eight of the competition because this means we have stayed in the World Group, while it also gives us a chance to carry on with our title defence,” Troicki told reporters.
“We are through to the quarter-finals, we know it’s going to be very tough against Sweden and we hope to have our best player Novak Djokovic back for that tie.”
Australian Open champion Djokovic missed the tie to concentrate on the Indian Wells event which begins this week.
In Zagreb, 2005 champions Croatia levelled 2-2 with Germany after Marin Cilic defeated Philipp Kohlschreiber 6-2 6-3 7-6 but Ivo Karlovic, who in Saturday’s doubles broke Andy Roddick’s serving speed record with a 156 mph (251 kms) rocket, was beaten by Petzschner 6-4 7-6 7-6.
“I got so much support from my team mates,” Petzschner told reporters. “It is just unbelievable that it ends like this. Absolutely crazy.”
France will be Germany’s quarter-final opposition after Guy Forget’s injury-weakened side beat Austria inside an airport hangar at Vienna airport. Jeremy Chardy won the fifth rubber against Martin Fischer 2-6 7-6 6-3 6-3 when victory appeared to slipping from their grasp.
Kazakh Andrey Golubev beat Wimbledon runner-up Tomas Berdych 7-5 5-7 6-4 6-2 to drag his side level before Mikhail Kukushkin held his nerve to beat Jan Hajek 6-4 6-7 7-6 6-0 and send his jubilant side through to a clash with Argentina.