Reilly Opelka and Brandon Nakashima both came through lengthy three-set battles to give their team a winning lead in the Group C opener in Zhuhai, China.
Olympic doubles silver-medallists Rajeev Ram and Austin Krajicek then beat Matias Soto and Tomas Barrios Vera to wrap up a 3-0 victory and join Germany at the top of the table.
Captain Bob Bryan was unable to call upon the likes of US Open runner-up Taylor Fritz, Frances Tiafoe or Tommy Paul but his team showed its strength in depth to win a tricky tie.
Opelka, ranked 309th in the world, beat 116th-ranked Cristian Garin 6-3, 4-6, 7-6(3) before Nakashima, the world number 40, beat Alejandro Tabilo 7-6(5), 2-6, 7-6(3).
Ram and Krajicek also needed three sets in the doubles to give 32-time Davis Cup winners the US the perfect start as they bid to reach the last eight for the second time since the new format was introduced in 2019.
Four groups of four nations are being contested in four different cities - Zhuhai, Bologna, Valencia and Manchester - with the top two from each group progressing to the final eight-nation knockout round in Malaga in November.
Later on Wednesday, Carlos Alcaraz is expected to line up for Spain against the Czech Republic in Group B in Valencia while Britain take on Finland in Group D in Manchester.
The day's other tie features reigning champions Italy against Brazil in Bologna in Group A.
Australia beat France in Group B on Tuesday while Germany beat Slovakia in Group C, Belgium beat the Netherlands in Group A and Canada were victorious against Argentina in Group D.
