It was an important victory for the world No.1 as Alexander Zverev had earlier registered a 6-4 6-2 6-2 success over David Ferrer to give the visitors an early advantage.
Nadal was equally impressively in his first outing since the Australian Open though, and the tie is evenly-poised heading into the second day of battle on the red dirt in Valencia.
“It was a positive match,” Nadal told DavisCup.com. “I won in straight sets and it was a solid match. After a while without being on court it’s always a great feeling to be back in front on my crowd – so I’m very happy for that.
“I was solid and did not make many mistakes. I was feeling comfortable again on clay so that it’s important to me. It’s always a great feeling to play at home in the Davis Cup and it was an unforgettable day.
“Coming back after injury is always difficult, but in front of my crowd, it’s a little less difficult.”
The results also went to plan on the first day of the Italy-France contest in Genoa.
Lucas Pouille fired the away side into the lead with a 6-3 6-2 4-6 3-6 6-1 win over Andreas Seppi before Fabio Fognini restored parity by overcoming Jeremy Chardy 6-7(6) 6-2 6-2 6-3.
Croatia and Kazakhstan are also level at one apiece after the first day.