The world number two turned on a masterclass of power and precision as he brushed aside Croatia's Ivan Dodig 6-4 6-3 6-3 to lead a trio of Spanish men into the fourth round.
French Open runner-up David Ferrer also moved through, beating Mikhail Kukushkin 6-4 6-3 4-6 6-4, while a third Spaniard, Tommy Robredo, ended the Cinderella run of British qualifier Dan Evans, winning 7-6 (6) 6-1 4-6 7-5.
Nadal has been in great form in the past month, winning warm-up tournaments in Montreal and Cincinnati. He has not dropped a single set in getting to the last 16 at Flushing Meadows and believes he is still improving.
"I played better today than in the previous matches. (That's) always a positive thing," he said.
"I started the match with a high intensity. I lost to Ivan the last time we played in Montreal and he won two hard matches here against Fernando Verdasco, a lefty like me, and Nikolay Davydenko.
"I think I played my best match of the week so far today."
Nadal's next opponent is Germany's Philipp Kohlschreiber, who beat towering American John Isner 6-4 3-6 7-5 7-6 (5), with Roger Federer looming as a possible quarter-final opponent.
The two great rivals have never played each other at the year's final Grand Slam, but could meet next week.
Federer, playing the feature night match at an buzzing Arthur Ashe Stadium, doled out a 6-3 6-0 6-2 hammering to Frenchman Adrian Mannarino but knows the focus is already on the possible meeting with Nadal.
"I have gone through that my entire career, people talking about our matches even before the tournament started," the Swiss said.
"We're used to it. We know how to handle it. Clearly I think we both hope it's going to happen this time for the first time in New York."