Despite Germany reaching the quarterfinals for the first time in three years, however, home supporters were angered by the no-show of three German players for the other reverse singles match with the result already decided.
Tommy Haas and Philipp Kohlschreiber won their doubles match Saturday for an unassailable 3-0 lead, after Kohlschreiber and Florian Mayer had won their singles on Friday.
The Spaniards were awarded a walkover in the fourth rubber when Kohlschreiber pulled out against Spanish No. 1 Feliciano Lopez, with Mayer and Haas also unavailable.
"All three of us have knocks and are exhausted and we cannot play," the 35-year-old Haas said. "I think it's time to change a few rules in the Davis Cup," he added, referring to matches when the result is already decided.
German captain Carsten Arriens was whistled and heckled by fans when he announced there would only be one match.
"I can fully understand their anger," said Arriens, who struggled to make himself heard as he tried to placate the crowd.
Haas, Kohlschreiber and Mayer were also subjected to loud whistles as they took their places for Brands' match.
"On the one hand I can understand people's frustration but you have to think of your own health from time to time," Kohlschreiber said.
German Tennis Federation president Karl-Georg Altenburg said all three players were examined by an independent doctor associated with the International Tennis Federation "and he said he couldn't take responsibility if they play."
Brands, the only fit German player, hit 12 aces in defeating Bautista Agut in 1 hour, 25 minutes.
Germany, which last won the trophy in 1993, plays France in the quarterfinals in April, while five-time champion Spain faces a World Group playoff in September after its second successive first-round exit.