Germany's 4-1 Davis Cup World Group win over Spain in Frankfurt was soured on Sunday as the hosts controversially forfeited one match due to injuries.
Three players were deemed unfit, leaving Daniel Brands as the only player left, but he enjoyed a 7-6 (7-5) 6-4 win over Roberto Bautista Agut in Sunday's fifth and final rubber.
German captain Carsten Arriens was forced to forfeit Sunday's opening singles rubber between Philipp Kohlschreiber and Feliciano Lopez, which did not impress the home crowd.
"The three players are not in a position to play; the fact we must forfeit a game is not ideal," Arriens told the 5000 spectators, to jeers in the Frankfurt arena.
In Saturday's doubles rubber, Germany's Tommy Haas and Kohlschreiber enjoyed a four-set win over Spain's Fernando Verdasco and David Marrero.
But the victory came at a cost with Kohlschreiber picking up a thigh problem and Haas aggravating a shoulder injury, as had Friday's singles winner Florian Mayer.
"All three of us are all really beat up - we're flat. There's no way we can play," said Haas.
The German Tennis Union (DTB) said the trio had all been seen by an International Tennis Federation (ITF) doctor.
"An official ITF doctor has examined all the players and could not be responsible for them playing," said DTB president Karl Altenburg.
"We will assess what happened later in calm."
Ex-German professional Nicolas Kiefer criticised the decision to forfeit.
"An ITF doctor? I've never heard of that before," he said.
"It is a pity and sad. It has tarnished everything which has been built up in the last two days.
"From the outside, this is not a good look for us."
In the one match that was played, 26-year-old Brands needed less than an hour and half to win as he blasted down 12 aces and never relinquished control of the rubber after taking the first set tiebreaker.
Germany had taken an unassailable 3-0 lead on Saturday which put them into an away quarter-final against France, who beat Australia 5-0.
