But the 19-time Grand Slam winner struggled in the heat and humidity of Sydney, crashing 6-4, 7-6 (7/3) to the 11th-ranked Belgium. It was a rare defeat while playing for his country, who he helped to victory in the Davis Cup in November.
It sent the tie to a decisive doubles match, with Nadal returning to partner Pablo Carreno Busta against Sander Gille and Joran Vliegen in a gritty 6-7 (7/9), 7-5, 10-7 win.
"It was tough, because for us it was a big change from Perth to here, not much time to adapt and the conditions were heavy, the humidity and playing against big players," said Nadal.
"But as a team we are super happy to be in the semi-finals."
Spain's group games during the round-robin phase of the inaugural team event were played in Perth, where the air was much drier.
Nadal, who had not dropped a set this year before meeting Goffin, was dripping in sweat for much of his singles match and used ice towels at the changeovers.
He struggled to find his rhythm, giving away nine break points in the first set.
Goffin had two more break points to go 5-3 up in the second, but Nadal clung on and became more offensive to take the match to a tiebreak before the Belgian closed it out for one of the biggest wins in his career. Spain will face Australia in the last four.