The three-time champion took control of the match when he broke the South Korean’s serve in the first set to grab a 4-2 lead and never looked back on a sunsoaked Arthur Ashe Stadium court, Reuters reported.
Nadal had been on court for just over two hours prior to his third round match after defeating John Millman in straight sets on Tuesday before getting a walkover into the third round when Thanasi Kokkinakis withdrew.
“I am happy to be playing on hardcourts and I am trying to play a little more aggressive,” Nadal said during his on-court interview.
Nadal will have his work cut out when he meets big-serving 2014 champion Marin Cilic on today, who defeated John Isner 7-5, 3-6, 7-6(6) 6-4.
Nadal said the key was to toppling an opponent like Cilic was holding serve and making the most of his opportunities when receiving.
“Chances are not a lot, so you need to be ready to expect a very tough one,” he told reporters.
“I need to be focused with my serve, as always. I need to be ready to accept the challenge that brings the competition in days like these ones.
“And I hope to be ready to play my highest level, because that’s what I am going to need.”
Naomi Osaka predicted she will strike up an exciting rivalry with American teen sensation Coco Gauff as part of a changing landscape at the top of women's tennis.
Defending US Open champion Osaka outclassed the tearful 15-year-old 6-3, 6-0 in just over an hour Saturday to advance to the fourth round, AFP reported.
But world number one Osaka, also the reigning Australian Open champion, anticipates the pair will wage battles on the court for years to come.
"I feel like of course we're going to play multiple times in the future. She's so young. That's definitely going to happen," Osaka said.
"She seems very intelligent, so I think there's automatically things that she's going to change the next time that we play.
"I'm not necessarily looking forward to that, but I think it will be fun for you guys to watch."
Gauff, who made a run to the Wimbledon fourth round last month on her Grand Slam debut, was seeking to become the youngest player to make the US Open last 16 since Russia's Anna Kournikova in 1996.
The emotional clash was followed by tearful on-court interviews, Osaka asking a reluctant Gauff to join her with the microphone as they met at the net.
"It was kind of instinctive because when I shook her hand, I saw that she was kind of tearing up a little. Then it reminded me how young she was," Osaka said.
"I wanted her to have her head high, not walk off the court sad. I want her to, like, be aware that she's accomplished so much and she's still so young."
Osaka goes on to face Swiss 13th seed Belinda Bencic for a place in the quarterfinals, and the top seed believes she is growing stronger the deeper she progresses at Flushing Meadows.
"The thing with me, though, is I get better as the tournament goes on," Osaka said. "It's not even a skill sort of thing, it's just I trust myself more.”