World number one Nadal saw off a battling Nikoloz Basilashvili, the first Georgian in a fourth round in NY, 6-3, 6-3, 6-7 (6/8), 6-4.
Nothing could separate them in the opening seven games, with just four points for the returners before Nadal earned a break in game eight after a poor backhand from Dominic.
Men's seventh seed Marin Cilic, who came through a marathon five-setter against Australian teenager Alex de Minaur on Saturday, resumes his quest for a second U.S. Open crown against Belgian 10th seed David Goffin.
Del Potro's yet to drop a set at his year's tournament. I had the passion to keep going always'. "He was playing great, hitting the ball very, very strong", he said. Thiem, energized after extending the match, held serve to start the set, while Nadal had brushed off the signs of discouragement from the end of the fourth.More news: Rockets, Suns swap bad contracts in four-player trade
"He's a fantastic player".
"It's a different kind of match than clay, but is still a tennis match", said Nadal. "He's a great guy, a close friend who will have many more opportunities to win the big titles". "So I didn't face one break point, and I didn't feel so much pressure on service games", said Thiem. "Happy for him that he's in quarter-finals here", he said.
Anderson admitted the better man beat him on the day‚ after having his serve broken three times in the match.
Williams, a six-time champion who missed last year's US Open as she gave birth to her daughter Olympia, is on a mission, seeking a title that would see her match Australian Margaret Court's all-time record of 24 major titles and let her avoid her first year since 2011 without a Grand Slam crown.
His 56 winners were erased by 59 unforced errors, three times as many as Nadal.More news: Couple Ordered To Turn Over Money Raised For Homeless Man
"Winning a big game and a very important game and a really tight game, I think it was just a relief", said Williams, who took control with a break in the next game and maintained that advantage until she fired a forehand victor on her first match point.
Anderson‚ 32‚ used his big serve and cool temperament to beat the Canadian 4-6‚ 6-3‚ 6-4‚ 4-6‚ 6-4 in the first ever match played under the new roof on court Louis Armstrong.
John Isner ground out yet another five-set win at the U.S. Open beating Milos Raonic 3-6 6-3 6-4 3-6 6-2 to advance to the quarter-finals of his home Grand Slam for the second time. But Nadal is more vulnerable in NY than he is at Roland Garros: At the French Open, he has an 86-2 career record and 11 titles.
Nadal edged a tense fifth-set tie-break to win 0-6 6-4 7-5 6-7 (4-7) 7-6 (7-5).More news: Saban called ESPN's Maria Taylor to apologize after interview
The ninth-seeded Austrian's three other appearances in the last-eight of a Slam have all been on the clay of Roland Garros in 2016, 2017 and 2018.